They are so busy that they have no time to do any sports, ______they need to do so.

The Green Great wall can stop the wind and the sand ____to the rich land in the south of China.

Kathy ________ a lot of Chinese when she was working in Beijing during the summer vacation.

Only when the firefighters put off the firewhatgreat damage it caused.

She dinner when there was a loud knock at the door.