巧辩When/while/as区别：[2]巧学英语语法

•教学目标：When while as的用法与区别

•中学重难点：when while as的用法与区别区别

•学生的困惑点：when while as的用法与区别区别

•区分方法：先语义后语法

•1.表示“当……时候”，“当……之后”之意 –1) 从句中的动词无论是延续性动词，还是短暂性动词都可以用when引导从句。 When I was watching TV, my mother came back. When he had finished his homework, he took a short rest. When I got to the airport, the guests had left. –2) 从句中的动词是延续性动词，可以用while或as替代when。 My father is cooking while my mother is reading newspapers. My father is cooking when my mother is reading newspapers. My father is cooking as my mother is reading  newspapers.

•2. 对两个同时进行的动作或状态进行对比时，多用while，亦可用as/when。 While she was making a phone call, I was writing aletter. When she was making a phone call, I was writing aletter. As she was making a phone call, I was writing a letter.

•3.表示一边……一边……只能用as。 The little girls sang as they went. The students took notes as they listened to the teacher.

4.表示“随着……”指时间的推移时，只能用as。 As time went by, the days became colder and colder. As Christmas are coming nearer, the children gotexcited. As  my grandfather is getting old, his memory is gettingpoorer.

总结： 表示当……时候，当……之后之意，多用when； 表示主从句正在进行的动作或状态的对比时多用while； 表示一边……一边……；只能用as；Ø表示随着……含义时，只能用as。