By the time he was twelve he ______ a chemistry lab of his own.

The College Entrance Examination __________near, so you should be prepared for it.

 Every possible means ___ to prevent the air pollution, but the sky is still not clear．

 When my sister phoned me, I could not hear clearly what she was _____.

—Is there any possible way to help them get rid of such a bad habit?—To tell the truth, it’s very hard. But we ________ on this problem, trying to improve the situation .