Shanghai Expo has been building an Expo Village for the participants, but other choices will also be ____ if the Expo Village does not satisfy their needs.
There are lots of plastic bags ____ in the river, ____ it very dirty.
--- Would you mind if I used your bike? --- ____.
The president spoke at the business meeting for nearly an hour without ____ his notes.
David worked hard at his lessons ____ he gained high grades in the exams.
As a young man, Zhou Enlai ____ the students movements and later ____ the Communist Party of China.