[单项选择]有关表面活性剂的正确表述是() A. 表面活性剂的浓度要在临界胶团浓度(cMC)以下,才有增溶作用 B. 表面活性剂用作乳化剂时,其浓度必须达到临界胶团浓度 C. 非离子表面活性的HLB值越小,亲水性越大 D. 表面活性剂均有很大毒性 E. 阳离子表面活性剂具有很强杀菌作用,故常用作杀菌和防腐剂
第33题: [单项选择]Why does the woman need to solve the problem A. She needs a new job. B. Her professor doesn’t want her to work. C. She wants to have time to do the assignments. D. She doesn’t think she can do the assignments. 参考答案:C 答案解析:[答案] [A]。