____on the project for 10 years ,he still felt it hard to make any achievements
问题描述：
____on the project for 10 years ,he still felt it hard to make any achievements
a.he works
b.having worked
c.he having worked
d.working
正确的选什么?并一个个解释一下为什么其他3个不行,都错在了那里?
答
B
主句和从句主语一致 省略其中一个主语!动词加ing .---主语一致的语法点
have done 表示完成语气用在此处比较合适