Unit7 The unknown world 重点语法：原因状语从句讲解及专练70题-2023-2024学年八年级英语下册重难点讲练全攻略（沪教牛津版）

学校:___________姓名：___________班级：___________ Unit7 The unknown world 重点语法：原因状语从句70题 目录 一、原因状语从句 1 二、because引导原因状语从句，40题 2 三、since引导原因状语从句，20题 6 四、as引导原因状语从句，10题 8 一、原因状语从句 定义：在句中用来说明主句原因的句子叫原因状语从句。 引导词：because（因为）, as （由于）, since （既然）, now（that）（既然） 时态:原因状语从句一般都是根据实际情况选用适当的时态。通常是主过从过,主现从现。 because, since和as的区别： 1）because引导的原因状语从句一般放于主句的后面，because从句位于句首时要用逗号分开，放在句末时，可不用逗号分开。because表示直接原因，语气最强，最适合回答why引导的疑问句。because of 也表示原因，但它后面不接从句，只能接名词，代词或动名词。 注意：because 和so 不可同时出现在一个句子里。 ①I do it because l like it. = I like it so I do it. ②We went by bus because it was cheaper. = It was cheaper so we went by bus. ③He can't go to school because of his illness. ③He can't go to school because of his illness. 2）since 引导的原因状语从句一般放于主句之前表示已知的、显然的理由（通常被翻译成“既然”＝now that），较为正式，语气比because弱。 ① Since you are free today, you had better help me with my mathematics. ② Since you don't trust him, you should not employ him. ③ Now(that)you are grown up, you should not rely on your parents. 3）as 引导原因状语从句时表示附带说明的“双方已知的原因”，含有对比说明的意味，语气比since弱，较为正式，位置较为灵活（常放于主句之前）。 ① As it is raining, you'd better take a taxi. ② As you are tired, you had better rest. ③ I went to bed early, as I was exhausted. 4）for引导的是并列句表示原因但并不说明主句行为发生的直接原因，只提供一些辅助性的补充说明，for引导的并列句只能放于主句之后并且必须用逗号将其与主句隔开。 ① He could not have seen me, for I was not there. ② He seldom goes out now, for he is very old. 二、because引导原因状语从句，40题 1．（23-24八年级下·全国·课后作业）________ her daughter hadn’t come back, ________ she looked worried. A．Because; so B．Because; / C．Though; but D．Though; / 2．（23-24八年级下·青海西宁·开学考试）I was late for school ________ the bus was too crowed for me to get on. A．because B．because of C．so D．but 3．（22-23八年级下·江苏南京·期中）Read the sentence. “I can tell her anything because she can keep a secret.” The underlined word “because” is used to ________. A．show time B．give examples C．join ideas together D．make new words 4．（23-24八年级·河北保定·期末）Everyone likes Tina ________ she is always ready to help others. A．because B．until C．so D．if 5．（23-24八年级·北京丰台·期末）Try to