第17题: [单项选择]系统溶剂分离法采取的溶剂,其极性顺序是 A. 从大到小 B. 从小到大 C. 先从大到小,后从小到大 D. 先从小到大,后从大到小 E. 从大到小,从小到大,再从大到小 参考答案:B 答案解析:系统溶剂萃取法利用各组分极性差别,依次以正己烷(或石油醚)、氯仿(或乙醚)、乙酸乙酯、正丁醇萃取,然后分别减压回收各有机层溶媒,则得到相应极性的中药成分。
第33题: [单项选择]______ our office, Mr. James voted against the proposal. A. (A) Representation B. (B) Representative C. (C) Representing D. (D) Representative of 参考答案:C 答案解析:Representing, which is a reduced modifying phrase, is the correct participle. Choice (A) is a noun.