选择题：Although they plant trees in this area every year,

题目内容：

Although they plant trees in this area every year, the tops of some hills are still ______. 　　
(A)blank
(B)hollow
(C)vacant
(D)bare

参考答案：

It is dangerous to ______ outdated(过时的) ideas and

It is dangerous to ______ outdated(过时的) ideas and theories.(A)cling to(B)strive

I was satisfied with her explanation, ______.(A)so my classmates were(B)so were

There was so much noise in the classroom that the teacher couldn.t make himself

The footballer made a (n) _____ gesture, which made the audience.s blood boil.

建筑石油沥青牌号的数值表示的是( 　　 )。　　　　(A)针入度平均值；(B)软化点平均值；(C)延度值；(D)沥青中的油分含量