The other scientists ______ to her ideas with a mixture of criticism and silence.
AIDS is said _______ the biggest health challenge to both men and women in that area over the past few years.
________ the problem of land erosion(侵蚀) getting more serious, the government is searching for a way to deal with it.
There are three students punished, two girls _______ .
In face of danger, we need to stay _______. Only in this way can we come up with good solutions.
— What about ______ bike?— Do you think it all right to buy him that bike as ______ birthday gift?