Question

完成下列句子1 we were having maths lesson___________(昨天这个时候)2 ____

Answer 1

1.this time yesterday.这个就不用解释了吧

2.When my mother cooked 当什么时候就是when ,发生在过去动作用过去时态

3.Xiaoming suddenly turned off the light.同上,要注意副词修饰动词

4.What were you doing,用过去式,相信你已经很明白what are you doing

5.Were they listening to the radio,同样用过去,句中强进行时态,要用过去正在进行时

when既可以跟持续性动作,也可以跟瞬间性动作,所以有大多数时候可以替代while,反而不可以,一般这种句子中,主句和从句中,用一个进行时态就好．