过去完成时(had)+(done)构成
我们是三点种到达的,但汽车离开了.
We arrived at 3 o'clock.But the bus(had)(left).
You'd better not to go home late.改错
You'd better not go home late.
She is enough old to look after(照顾)herself.She is old enough to look after(照顾)herself.