“Did you hear someone knocking at the door?” “Yes, I did. I heard him______three times.”[ ]

Your composition is full of mistakes. —I wish I _________more careful.

It’s our duty ________our city clean and beautiful.—Yes. We should do something for it.

Barry must have visited the Eiffel Tower before，________he?

Chris has learnt English for only three months.—______! His English is so good.