I learned a lot ___ in the countryside.A.working B.while working _英语解答

I learned a lot ___ in the countryside.
A.working B.while working C.when worked D.to work
请问为什么

人气：141 ℃　时间：2020-06-03 13:46:56

解答

省略,当主句从句的主语相同的时候,
从句中,可以省略主语和助动词
完整的：i learned a lot while I was working in the countryside.
省略,就是 ...while working ...