AmanwashitbyacaarwhenIby.为什么要用过去进行时不用一般现在时?

Question

A man was hit by a caar when I_______by.为什么要用过去进行时不用一般现在时?

Answer 1

和when i was walking in the steet,i saw him.这句话是一样的结构.“当我走在街上的时候,我看到他.”表示when引导的时间状语从句的动作（walk）和主句的动作（see）是同时发生的.
你的问题中也是一样,一个人被车撞了,当时我正好经过.When i was passing by,i saw a man was hit by a car.
可以改写为非谓语动词：(When) Passing by ,i saw a man was hit by a car.
还可用独立主格结构：i passing by,a man was hit by a car.
请注意比较句子的主语.