_________ by the teacher, Tom got into the classroom from the back door quietly.

______ better in 2010 World Expo is the duty of every citizen in Shanghai.

He made a mistake, so he told a lie to avoid ______.

I don’t want       any more trouble, you see?

The stone under her feet rolled; and as she was        into the river, she called out for help.

She wants her paintings   in the gallery, but we don t think they would be very popular.

   the safety of gas, the government has checked the city’s gas supply system thoroughly.

All the staff {n our company are considering   to the city centre for the fashion show.

______with several kinds of flowers and plants, our school looks much more beautiful．

Putting waste in different bins made it easier for it______．