______how to do the work several times,but he still doesn't kown how to do the work.A l have shown him B having been shown 为什么选A?主语不应该一致吗?难道是因为有连接词BUT吗?
问题描述：
______how to do the work several times,but he still doesn't kown how to do the work.
A l have shown him B having been shown 为什么选A?主语不应该一致吗?难道是因为有连接词BUT吗?
答
是因为but, but前后连接两个小分句,都应该有主谓结构
如果没有but ,就应该选B,作he still does't know how to do the work 的状语从句