Unit 4 Time to celebrate 频度副词和一般现在时2024-2025学年外研版英语七年级上册

Unit 4 Time to celebrate 频度副词和一般现在时 一、频度副词 频度副词一般是在英语中表示动作频率的副词，常见的副词有always, usually, often, sometimes, seldom，never等。具体含义及表示的频率大小如下： 在英语句子中，频度副词一般位于系动词、助动词、情态动词之后，或者行为动词之前： 1) 在系动词之后: She is usually very busy.她通常很忙。 2 ) 在助动词之后: I will never forget this holiday. 我永远不会忘记这个假期。 3) 在情态动词之后: You should always go to school on time. 你应该总是按时上学。 4) 在行为动词之前: We often go to the cinema. 我们经常去电影院看电影。 sometimes 可放在句首、句中、句末，often也可以放在句末: Sometimes she calls me. / She calls me sometimes. 她有时候给我打电话。 She calls me often. 她经常给我打电话。 注意：如果句中有两个助动词，频度副词一般放在第一个助动词之后。 We have never been given the chance to talk to him. 我们从未得到过与他对话的机会。 【基础过关练1】用一般现在时完成句子: Ⅰ. 选词填空：将频度副词按照频率大小写在相应的空格位置。 never, always, often, usually, sometimes Ⅱ. 改写句子：给下列句子在恰当的位置加上频度副词。 例：Mum buys some fruit on Sunday.  (often) →Mum often buys some fruit on Sunday. 1. I go to the library after school.  (often) _______________________________________________ 2. Susan talks to me.  (never) _______________________________________________ 3. The lesson starts at 8 o'clock.  (usually) _______________________________________________ 4. Does he have noodles for lunch?  (often) _______________________________________________ 5. They don't work at weekends.  (always) _______________________________________________ 二、Be动词的一般现在时 一、动词be的一般现在时形式：有三种形式，它随主语的变化而变化。 主语 动词be I am He / She / It is They /We / You are 二、动词be 的一般现在时的肯定句式 请观察下列例句，并补全结论。 1. I am Miss Zhao. 2. It is a black cat. 3. They are classmates. 【结论】：动词be 的一般现在时的肯定句式是：主语+动词be +其他。 三、动词be 的一般现在时的否定句式 请观察下列例句，并补全结论。 1. I am not Miss Zhao. 2. It is not (isn't) a black cat. 3. They are not (aren't) classmates. 【结论】：动词be 的一般现在时的否定句式是：主语+动词be+ not +其他。 四、动词be 的一般现在时的疑问句式 请观察下列例子，并补全结论。 1. —Are you Miss Zhao? —Yes, I am. / —No, I'm not. 2. —Is it a black cat? —Yes, it is. / —No, it isn't. 3. —Are they classmates? —Yes, they are. / —No, they aren't. 【结论】：动词be 的一般现在时的疑问句式是“动词be+主语+其他?”，其肯定回答是“Yes, 主语+动词be”；否定回答是“No, 主语+动词be+ not”。 注意：在否定句式和否定回答中，动词be 可与not 缩写，但am 与not不能缩写。 【基础过关练2】 Ⅰ. 完成句子 动词be的一般现在时有________种形式，分别是：_____________________。 Ⅱ. 用动词be的适当形式填空 1. It ________ warm today. 2. I ________ Liu Lili. 3. She ________ a nice girl. 4. ________ you from England? 5. Betty and I ________ in Class 4. 6. The dog ________ white and black. Ⅲ. 句型转换 1. It is a bird.   (改为否定句) It ________ a bird. 2. I am 12 years old.   (改为否定句) I ________ ________ 12 years old. 3. Daming is from Beijing. (改为一般疑问句并补全肯定答语) —________ Daming from Beijing? —Yes, ________ ________. 4. The pencil is on the desk. (改为一般疑问句并补全否定答语) —________ the pencil on the desk? —No, ________ ________. 5. They are American.  (改为一般疑问句并补全否定答语) —________ they American? —No, ________ ________. 三、行为动词的一般现在时（一） 一、一般现在时肯定句结构：“主语+谓语动词原形+其他”。如： 1. I play basketball in the playground. 我在操场打篮球。 2. You draw very well. 你画的非常好。 3. We like the blue chairs in the classroom. 我们喜欢教室里的蓝椅子。 4. They work in America. 他们在美国工作。 5. Chen Xi and Chen Li eat breakfast at home. 陈曦和陈丽在家吃早餐。 二、一般现在时否定句结构：“主语+ don’t +谓语动词原形+其他”。如： 1. I don’t play basketball in the playground. 2. You don’t draw very well. 3. We don’t like the blue chairs in the classroom. 4. They don’t work in America. 5. Chen Xi and Chen Li don’t eat breakfast at home. 三、一般现在时一般疑问句结构：“Do +主语+谓语动词原形+其他?”，肯定回答为“Yes, 主语+do”，否定回答为“No, 主语+ don’t”。如： 1. Do you play basketball in the playground? —Yes, I do. —No, I don’t. 2. Do I draw very well? —Yes, you do. —No, you don’t. 3. Do you like the blue chairs in the classroom? —Yes, we do. —No, we don’t. 4. Do they work in America? —Yes, they do. —No, they don’t. 5. Do Chen Xi and Chen Li eat breakfast at home? —Yes, they do. —No, they don’t. 【基础过关练3】 Ⅰ. 选词填空 have, get, close, work, open, play, wash 1. —You ________ basketball very well. —Thank you. 2. I ________ my face after I ________ up. 3. They ________ in the same hospital. 4. We ________ bread for breakfast on Sunday. 5. The shops ________ at 9 o'clock and ________ at 7:30. Ⅱ. 改为否定句 1. I like these books. ___________________________________________ 2. We go shopping on Sunday. ___________________________________________ 3. They know Lisa's telephone number. ___________________________________________ 4. You do the same work every day. ___________________________________________ 四、行为动词的一般现在时（二） 主语是第三人称单数时的行为动词的一般现在时。 一、肯定句结构：主语+谓语动词第三人称单数形式+其他. 如： 1. He gets up at six o'clock in the morning. 2. It eats many kinds of food every day. 3. That cat often sleeps on the bed. 二、否定句结构：主语+does not(doesn't)+谓语动词原形+其他. 如： 1. He doesn't get up at six o'clock in the morning. 2. It doesn't eat many kinds of food every day. 3. That cat doesn't often sleep on the bed. 三、一般疑问句及答语结构：Does+主语+谓语动词原形+其他? 肯定回答Yes, 主语(代词)+does. / 否定回答No, 主语(代词)+doesn’t. 如： 1. —Does he get up at six o'clock in the morning? —Yes, he does. / No, he doesn't. 2. —Does it eat many kinds of food every day? —Yes, it does. / No, it doesn't. 3. —Does the cat often sleep on the bed? —Yes, it does. / No, it doesn't. 四、一般现在时特殊疑问句的结构：“特殊疑问词(不作主语)+do / does+主语+动词原形+其他？”。 特殊疑问词有how, what, when, where，分别用来询问方式、事物、时间、地点等。如： 1. How do they go to school? 2. What does she have for dinner? 3. When does he play basketball at school? 4. Where do you go at the weekend? 注意：回答特殊疑问句时，不能用“Yes / No”，而应根据具体情况作出相应的回答。如： 1. —How do you go to work? —By bus. 2. —Where does Mary go at the weekend? —To the library. 【基础过关练4】 1）用动词的适当形式填空 1. I ____________ (like) swimming. 2. He _________ (read) English every day. 3. We _________ (go) to school at seven in the morning. 4. Mike________ (go) to school at seven in the morning. 5. My mother________ (like) ______ (go) shopping. 6. I can ________ (draw) many beautiful pictures. 7. She _________ (make) a model plane. 8. Do you ________ (like) _________ (run)? 9. Does he _________ (like) _________ (jump)? 10. Does Nancy _________ (grow) flowers on Saturday? 11. The teachers ________ (like) ___________ (dance). 12. The teacher ________ (like) ____________ (dance). 13. The students ___________ (speak) English in class. 14. The student _________ (speak) Chinese after class. 15. Let's ____________ (go) and play football. 16. He _____________ (not like) swimming. 17. I'm sorry ____________ (hear) that. 18. Wang Bing often ____________ (write) E-mails to her. 19. _________ you study English at school? 20. __________your sister study English at school? 2）用所给的人称改写句子 1. I take photos on Sunday. (Mike) 2. We grow beautiful flowers. (He) 3. They like collecting stamps. (Ben) 4. You listen to music carefully. (My aunt) 5. The women clean the classroom every day. (She) 3）改写句子 1. Do you often play football after school? (肯定回答) 2. I have many books. （改为否定句） 3. Gao Shan's sister likes playing table tennis.（改否定句） 4. She lives in a small town near New York. （改一般疑问句） 5. They watch TV every day. （改为一般疑问句） 6. He doesn't run fast. （改为肯定句） 7. My dogs run fast. （改为否定句） 8. Mike has two letters for him. （改为一般疑问句） 9. My sister usually washes some clothes on Saturday. （改为一般疑问句） 10. Mingming usually waters the flowers every day （改为否定句） 【能力提升训练--链接中考】 1.（2023·甘肃白银·统考中考真题） If you heat ice, it ________ into water. A．turns B．turned C．was turning D．has turned 2.（2023·四川凉山·统考中考真题） —Are you going to see the panda Huahua at the Chengdu Research Base tomorrow? —Sure. If I ________ the chance, perhaps I can’t see her any longer this holiday. A．miss B．missed C．will miss 3. (2022湖南郴州中考)—The song Together for a Shared Future is very popular now. —That's for sure! Both the young and the old _______it. A. likes B. like C. liked 4. (2022辽宁盘锦中考) 8. The little boy won’t go to sleep unless his mom________him a story. A. tells B. told C. is telling D. will tell 5.（2022广西百色中考）I don't know if it tomorrow, but if it , I'll stay at home. A．will rain；rains B．will rain；will rain C．rains；will rain D．rains；rains 6. (2022湖北江汉油田、潜江、天门、仙桃) He ______ newspapers at 8:00 every evening. A. reads B. is reading C. was reading D. has read 7.（2022 黑龙江龙东中考）—I don’t know when Susan ________. —Don’t worry. When she ________, I will tell you. A. comes; will come B. will come; comes C. come; comes 8. (2022台湾) Aunt Gina has lived in this town for more than sixty years, so she _____ it very well. A. will know B. knew C. knows D.was going to know 9. (2022江苏扬州中考) Xia Sen ＿＿＿＿ a simple life and saves her money for donations. A. lives B. lived C. was living D. will live 10. (2022湖北武汉) —I don’t think sixteen-year-olds should be allowed to drive. —I __________. It’s not safe. A. agree B. agreed C. will agree D. had agreed 2 学科网（北京）股份有限公司 $$ Unit 4 Time to celebrate 频度副词和一般现在时 一、频度副词 频度副词一般是在英语中表示动作频率的副词，常见的副词有always, usually, often, sometimes, seldom，never等。具体含义及表示的频率大小如下： 在英语句子中，频度副词一般位于系动词、助动词、情态动词之后，或者行为动词之前： 1) 在系动词之后: She is usually very busy.她通常很忙。 2 ) 在助动词之后: I will never forget this holiday. 我永远不会忘记这个假期。 3) 在情态动词之后: You should always go to school on time. 你应该总是按时上学。 4) 在行为动词之前: We often go to the cinema. 我们经常去电影院看电影。 sometimes 可放在句首、句中、句末，often也可以放在句末: Sometimes she calls me. / She calls me sometimes. 她有时候给我打电话。 She calls me often. 她经常给我打电话。 注意：如果句中有两个助动词，频度副词一般放在第一个助动词之后。 We have never been given the chance to talk to him. 我们从未得到过与他对话的机会。 【基础过关练1】用一般现在时完成句子: Ⅰ. 选词填空：将频度副词按照频率大小写在相应的空格位置。 never, always, often, usually, sometimes Ⅱ. 改写句子：给下列句子在恰当的位置加上频度副词。 例：Mum buys some fruit on Sunday.  (often) →Mum often buys some fruit on Sunday. 1. I go to the library after school.  (often) _______________________________________________ 2. Susan talks to me.  (never) _______________________________________________ 3. The lesson starts at 8 o'clock.  (usually) _______________________________________________ 4. Does he have noodles for lunch?  (often) _______________________________________________ 5. They don't work at weekends.  (always) _______________________________________________ 参考答案 Ⅰ. 1. never   2. sometimes   3. often   4. usually   5. always Ⅱ. 1. I often go to the library after school. 2. Susan never talks to me. 3. The lesson usually starts at 8 o'clock. 4. Does he often have noodles for lunch? 5. They don't always work at weekends. 二、Be动词的一般现在时 一、动词be的一般现在时形式：有三种形式，它随主语的变化而变化。 主语 动词be I am He / She / It is They /We / You are 二、动词be 的一般现在时的肯定句式 请观察下列例句，并补全结论。 1. I am Miss Zhao. 2. It is a black cat. 3. They are classmates. 【结论】：动词be 的一般现在时的肯定句式是：主语+动词be +其他。 三、动词be 的一般现在时的否定句式 请观察下列例句，并补全结论。 1. I am not Miss Zhao. 2. It is not (isn't) a black cat. 3. They are not (aren't) classmates. 【结论】：动词be 的一般现在时的否定句式是：主语+动词be+ not +其他。 四、动词be 的一般现在时的疑问句式 请观察下列例子，并补全结论。 1. —Are you Miss Zhao? —Yes, I am. / —No, I'm not. 2. —Is it a black cat? —Yes, it is. / —No, it isn't. 3. —Are they classmates? —Yes, they are. / —No, they aren't. 【结论】：动词be 的一般现在时的疑问句式是“动词be+主语+其他?”，其肯定回答是“Yes, 主语+动词be”；否定回答是“No, 主语+动词be+ not”。 注意：在否定句式和否定回答中，动词be 可与not 缩写，但am 与not不能缩写。 【基础过关练2】 Ⅰ. 完成句子 动词be的一般现在时有________种形式，分别是：_____________________。 Ⅱ. 用动词be的适当形式填空 1. It ________ warm today. 2. I ________ Liu Lili. 3. She ________ a nice girl. 4. ________ you from England? 5. Betty and I ________ in Class 4. 6. The dog ________ white and black. Ⅲ. 句型转换 1. It is a bird.   (改为否定句) It ________ a bird. 2. I am 12 years old.   (改为否定句) I ________ ________ 12 years old. 3. Daming is from Beijing. (改为一般疑问句并补全肯定答语) —________ Daming from Beijing? —Yes, ________ ________. 4. The pencil is on the desk. (改为一般疑问句并补全否定答语) —________ the pencil on the desk? —No, ________ ________. 5. They are American.  (改为一般疑问句并补全否定答语) —________ they American? —No, ________ ________. 答案 Ⅰ. 三; am, is, are Ⅱ. 1. is   2. am   3. is   4. Are   5. are   6. is Ⅲ. 1. isn't   2. am not   3. Is; he is   4. Is; it isn't   5. Are; they aren't 三、行为动词的一般现在时（一） 一、一般现在时肯定句结构：“主语+谓语动词原形+其他”。如： 1. I play basketball in the playground. 我在操场打篮球。 2. You draw very well. 你画的非常好。 3. We like the blue chairs in the classroom. 我们喜欢教室里的蓝椅子。 4. They work in America. 他们在美国工作。 5. Chen Xi and Chen Li eat breakfast at home. 陈曦和陈丽在家吃早餐。 二、一般现在时否定句结构：“主语+ don’t +谓语动词原形+其他”。如： 1. I don’t play basketball in the playground. 2. You don’t draw very well. 3. We don’t like the blue chairs in the classroom. 4. They don’t work in America. 5. Chen Xi and Chen Li don’t eat breakfast at home. 三、一般现在时一般疑问句结构：“Do +主语+谓语动词原形+其他?”，肯定回答为“Yes, 主语+do”，否定回答为“No, 主语+ don’t”。如： 1. Do you play basketball in the playground? —Yes, I do. —No, I don’t. 2. Do I draw very well? —Yes, you do. —No, you don’t. 3. Do you like the blue chairs in the classroom? —Yes, we do. —No, we don’t. 4. Do they work in America? —Yes, they do. —No, they don’t. 5. Do Chen Xi and Chen Li eat breakfast at home? —Yes, they do. —No, they don’t. 【基础过关练3】 Ⅰ. 选词填空 have, get, close, work, open, play, wash 1. —You ________ basketball very well. —Thank you. 2. I ________ my face after I ________ up. 3. They ________ in the same hospital. 4. We ________ bread for breakfast on Sunday. 5. The shops ________ at 9 o'clock and ________ at 7:30. Ⅱ. 改为否定句 1. I like these books. ___________________________________________ 2. We go shopping on Sunday. ___________________________________________ 3. They know Lisa's telephone number. ___________________________________________ 4. You do the same work every day. ___________________________________________ 答案 Ⅰ. 1. play   2. wash; get   3. work   4. have   5. open; close Ⅱ. 1. I don't like these books. 2. We don't go shopping on Sunday. 3. They don't know Lisa's telephone number. 4. You don't do the same work every day. 四、行为动词的一般现在时（二） 主语是第三人称单数时的行为动词的一般现在时。 一、肯定句结构：主语+谓语动词第三人称单数形式+其他. 如： 1. He gets up at six o'clock in the morning. 2. It eats many kinds of food every day. 3. That cat often sleeps on the bed. 二、否定句结构：主语+does not(doesn't)+谓语动词原形+其他. 如： 1. He doesn't get up at six o'clock in the morning. 2. It doesn't eat many kinds of food every day. 3. That cat doesn't often sleep on the bed. 三、一般疑问句及答语结构：Does+主语+谓语动词原形+其他? 肯定回答Yes, 主语(代词)+does. / 否定回答No, 主语(代词)+doesn’t. 如： 1. —Does he get up at six o'clock in the morning? —Yes, he does. / No, he doesn't. 2. —Does it eat many kinds of food every day? —Yes, it does. / No, it doesn't. 3. —Does the cat often sleep on the bed? —Yes, it does. / No, it doesn't. 四、一般现在时特殊疑问句的结构：“特殊疑问词(不作主语)+do / does+主语+动词原形+其他？”。 特殊疑问词有how, what, when, where，分别用来询问方式、事物、时间、地点等。如： 1. How do they go to school? 2. What does she have for dinner? 3. When does he play basketball at school? 4. Where do you go at the weekend? 注意：回答特殊疑问句时，不能用“Yes / No”，而应根据具体情况作出相应的回答。如： 1. —How do you go to work? —By bus. 2. —Where does Mary go at the weekend? —To the library. 【基础过关练4】 1）用动词的适当形式填空 1. I ____________ (like) swimming. 2. He _________ (read) English every day. 3. We _________ (go) to school at seven in the morning. 4. Mike________ (go) to school at seven in the morning. 5. My mother________ (like) ______ (go) shopping. 6. I can ________ (draw) many beautiful pictures. 7. She _________ (make) a model plane. 8. Do you ________ (like) _________ (run)? 9. Does he _________ (like) _________ (jump)? 10. Does Nancy _________ (grow) flowers on Saturday? 11. The teachers ________ (like) ___________ (dance). 12. The teacher ________ (like) ____________ (dance). 13. The students ___________ (speak) English in class. 14. The student _________ (speak) Chinese after class. 15. Let's ____________ (go) and play football. 16. He _____________ (not like) swimming. 17. I'm sorry ____________ (hear) that. 18. Wang Bing often ____________ (write) E-mails to her. 19. _________ you study English at school? 20. __________your sister study English at school? 答案：1) 1. like 2. reads 3. go 4. goes 5. likes going 6. draw 7. makes 8. like running 9. like jumping 10. grow 11. like dancing 12. likes dancing 13. speak 14. speaks 15. go 16. doesn’t lilke 17. to hear 18. writes 19. Do 20. Does 2）用所给的人称改写句子 1. I take photos on Sunday. (Mike) Mike takes photos on Sunday. 2. We grow beautiful flowers. (He) He grows beautiful flowers. 3. They like collecting stamps. (Ben) Ben likes collecting stamps. 4. You listen to music carefully. (My aunt) My aunt listens to music carefully. 5. The women clean the classroom every day. (She) She cleans the classroom every day. 3）改写句子 1. Do you often play football after school? (肯定回答) Yes, I do. 2. I have many books. （改为否定句） I don’t have many books. 3. Gao Shan's sister likes playing table tennis.（改否定句） Gao Shan’s sister doesn’t like playing table tennis. 4. She lives in a small town near New York. （改一般疑问句） Does she live in a small town near New York? 5. They watch TV every day. （改为一般疑问句） Do they watch TV every day. 6. He doesn't run fast. （改为肯定句） He runs fast. 7. My dogs run fast. （改为否定句） My dogs don’t run fast. 8. Mike has two letters for him. （改为一般疑问句） Does Mike have two letters for him? 9. My sister usually washes some clothes on Saturday. （改为一般疑问句） Does your sister usually wash any clothes on Saturday? 10. Mingming usually waters the flowers every day （改为否定句） Mingming doesn’t usually water the flowers every day. 【能力提升训练--链接中考】 1.（2023·甘肃白银·统考中考真题） If you heat ice, it ________ into water. A．turns B．turned C．was turning D．has turned 【答案】A 句意：如果你加热冰，它就会变成水。 考查动词时态。if引导的条件状语从句，遵循“主将从现”原则，但是主句是客观事实，还是用一般现在时。故选A。 2.（2023·四川凉山·统考中考真题） —Are you going to see the panda Huahua at the Chengdu Research Base tomorrow? —Sure. If I ________ the chance, perhaps I can’t see her any longer this holiday. A．miss B．missed C．will miss 【答案】A句意：——你明天要去成都研究基地看熊猫花花吗？——当然。如果我错过了这个机会，也许这个假期我就再也见不到她了。 考查动词时态。if引导的条件状语从句，遵循“主将从现”原则，从句用一般现在时，主语是I，动词用原形，故选A。 3. (2022湖南郴州中考)—The song Together for a Shared Future is very popular now. —That's for sure! Both the young and the old _______it. A. likes B. like C. liked 【答案】 B 考查动词时态。句意：—那首一起向未来的歌现在很受欢迎。—那是当然！年轻人和老人都喜欢它。根据句子主语是“Both the young and the old”为复数且问句的“now”表示一般现在时可知用like, 故选B。 4. (2022辽宁盘锦中考) 8. The little boy won’t go to sleep unless his mom________him a story. A. tells B. told C. is telling D. will tell 【答案】A 考查时态。句意：这个小男孩不会睡觉除非她的妈妈给他讲故事。unless引导的句子要用一般现在时态表示将来。故选A。 5.（2022广西百色中考）I don't know if it tomorrow, but if it , I'll stay at home. A．will rain；rains B．will rain；will rain C．rains；will rain D．rains；rains 【答案】A 考查if从句。由句意“我不知道明天是否会下雨, 但如果下雨, 我会呆在家里。”可知, 第一个空格处所在句为if意为“是否”, 引导的宾语从句, 主句为一般现在时, 从句用所需时态, 由tomorrow可知, 应用一般将来时, 构成为will+动词原形；第二个空格所在句if意为“如果”, 引导条件状语从句, 主句为一般将来时, 从句用一般现在时, 故选A。 6. (2022湖北江汉油田、潜江、天门、仙桃) He ______ newspapers at 8:00 every evening. A. reads B. is reading C. was reading D. has read 【答案】A考查动词时态。由时间状语at 8:00 every evening可知，使用一般现在时。故选A。 7.（2022 黑龙江龙东中考）—I don’t know when Susan ________. —Don’t worry. When she ________, I will tell you. A. comes; will come B. will come; comes C. come; comes 【答案】B 考查复合句中的动词时态。句意：——我不知道苏珊什么时候来。——不用担心。她来的时候，我会告诉你的。空1是宾语从句，表示“不知道Susan什么时候来”，用一般将来时；空2是when引导的时间状语从句，遵循“主将从现”原则，空处需用一般现在时。故选B。 8. (2022台湾) Aunt Gina has lived in this town for more than sixty years, so she _____ it very well. A. will know B. knew C. knows D.was going to know 【答案】C 考查动词的时态。句意：吉娜阿姨在这镇子生活了六十多年了，因此她很了解它。 强调现在很了解，因此用一般现在时。 9. (2022江苏扬州中考) Xia Sen ＿＿＿＿ a simple life and saves her money for donations. A. lives B. lived C. was living D. will live 【答案】A考查动词时态辨析。句意：夏森过着简朴的生活，把钱攒起来捐钱。根据and后面saves提示，用动词第三人称单数形式lives完成句子。故选A。 10. (2022湖北武汉) —I don’t think sixteen-year-olds should be allowed to drive. —I __________. It’s not safe. A. agree B. agreed C. will agree D. had agreed 【答案】A 考查动词时态。——我认为十六岁的孩子不应该被允许开车。——我同意，这不安全。表示说话当时的状态，因此用一般现在时。 2 学科网（北京）股份有限公司 $$