题目内容：

Can you remember who -------(teach) you to ride a bike when you were young?
为什么不是was teaching呢,有when,且teach是可延续的

优质解答

从后面的were可以知道是过去时态,所以必须用taught.
之余为什么不用was teaching就更加容易理解了.
was teaching是过去进行时.它使用的时间条件就是必须要有对应的时间点!注意：是时间点,而从句部分是when you were young,这是一个时间段!