She tried to explain this program by_____of sign language.

（ ） is careless when disposing of his wastes.

All of them are （ ） at Lana’s achievement.

Nothing can _____ unless you tell us the truth.

She has （ ） chance to win the election as her opponent is too strong.

He studies so hard to avoid （ ） at the bottom of the class.

The Quality Control Staff is responsible _____ the quality of the products that come out of the factory.

The tribe had been living in that part of the area for generations until the civil war ______.

I shall have a companion in the house after all these （ ） years．

（ ） the past year as an exchange student in Hong Kong, Linda appears more mature than those of her age.

Language belongs to each member of the society, to the cleaner（ ） to the professor.

To be frank, （ ） is a great relief to have the task fulfilled in so short a time.