高中英语by-the-time-的用法(共11张PPT)

By the time by the time意为“到……时候（为止）”，是一个介词短语，在句中经常起连词作用，引导时间状语从句。它的主要用法如下： 　　1. 如果从句中的谓语动词是一般过去时，那么主句中的谓语动词通常用过去完成时，表示“截止到从句动作发生时，主句动作已经完成，即过去的过去”。例如： 　　By the time he was fourteen years old，Einstein had learned advanced mathematics all by himself. 到14岁的时候，爱因斯坦就已经自学完了高等数学。 　　By the time he returned home，the rain had stopped. 等他回到家时，雨已经停了。 By the time I got to the station，the train had already gone。 By the time l got home，they had already left。 By the time I received his letter, he had left Shanghai. By the time he was 12, he had traveled to more than 30 countries to get his diseases cured. 2. 如果从句中的谓语动词为一般现在时/或现在完成时（表示将来），那么主句中的谓语动词常为将来完成时，表示“截止到将来某一时间为止，主句动作将已经完成”。 　　By the time John finishes his homework， his classmates shall have left to play football. 到约翰做完作业时，她的同学将已离开去伦踢足球了。 　　By the time you get back，I shall have finished the work. 到你回来时，我将已经把活做完了。 By the time I get home，they will have left。 By the time I graduate next year, I will have lived here for 5 years