第14题:[多选题] 不停电作业:系指() A. 本身不需要停电且无偶然触及带电部分可能的作业 B. 更换绑桩、涂写杆号牌、修剪树枝 C. 更换灯泡、检修外灯伞等作业 D. 以上都对 参考答案:ABCD
第15题: [单项选择]Differences in positions adopted by oxygen and hydrogen atoms account for variations in the crystalline structure of different forms of ice. A. are caused by B. explain C. derive from D. constitute 参考答案:B 答案解析:are caused by由…引起。explain解释。derive from源自。constitute制订,组成。 account for解释。
第18题: [单项选择]The residents, ______ had been damaged by the flood, were given help by the Red Cross. A. all their homes B. all whose homes C. all of whose homes D. all of their homes 参考答案:C 答案解析:根据句子结构我们可以看出,此处为非限制性定语从句,而A.和D.中没有关系代词,故可以排除。B.中虽有作定语的关系代词,但是whose homes 不能直接和all连用,因此只有C为正确答案。