There are a lot of computers in the lab,and they need professional __________ to make sure they can be in a good state.

To his relief, the company’s exports have been increasing ______ [ ]

Only 16 percent of China’s area ____ covered withforests, so ____of us should protect trees.

_______ the news, they are very happy.

study finds that sitting can shorten aperson’s life almost as much as smoking can, which _______ just how damaginginactivity can be.