Question

分析一下这句话的句子成分 为什么用while 为什么不是looking

while looked at the birds,they heard a mother bird chirp

Answer 1

这句话用while 引起时间状语表示＂当⋯⋯时候＂，正确。但是后面用looked 可就绝对错了，应改为 looking。实际上这里是省去了he was ，While they were looking at the birds, they heard a mother bird chirp. 当他们看鸟儿时，听见了一只鸟妈妈唧唧喳喳的叫声。

追答

句子成分如下：
while looking at the birds 状语从句省去they were 。
they 主语
heard 谓语
a mother bird 宾语
chirp 宾语补足语（省去to的不定式）

Answer 2

factors引导的是同位语从句，修饰前面那句话。