挑错题,factory workers (had to) work (very hard) before,(so) (had farmers).

问题描述:

挑错题,factory workers (had to) work (very hard) before,(so) (had farmers).
factory workers (had to) work (very hard) before,(so) (had
a b c d
farmers).
请问为什么呢?这句话很别扭是什么意思呢?

D,had要改为did,have to 的助动词不是have,而是do,要熟记.
祝楼主更上一层楼