第4题: [单项选择]The main idea of the third paragraph is stated in the ______. A. first sentence B. second sentence C. third sentence D. last sentence 参考答案:A 答案解析:读完第三段,可分析出第一句话即是这段的主题句,可概括全段的主要内容,后三句话是对第一句话的解释说明。
第30题: [多项选择]水闸按闸室结构形式可分为( )。 A. 开敞式 B. 分洪闸 C. 胸墙式 D. 涵洞式 E. 进水闸 参考答案:A,C,E
第31题: [单项选择]______ for your help, we'd never have been able to get over the difficulties. A. If we had not been B. Were it not C. If it were not D. Had it not been 参考答案:D 答案解析:本题意为:要不是你的帮忙,我们不会克服困难的。if引导的虚拟条件句中含有 should,had,were时,省略if将should,had,were提至主语之前。