问题
单项选择题
下列具有起昙现象的表面活性剂是
A．硬脂酸钠
B．月桂醇硫酸钠
C．硬脂醇硫酸钠
D．司盘-80
E．吐温-20
答案
参考答案：E
解析：某些含聚氧乙烯基的非离子型表面活性剂会产生起昙现象，如吐温类，应选E吐温-20。
搜题请搜索小程序“爱下问搜题”
下列具有起昙现象的表面活性剂是
A．硬脂酸钠
B．月桂醇硫酸钠
C．硬脂醇硫酸钠
D．司盘-80
E．吐温-20
参考答案：E
解析：某些含聚氧乙烯基的非离子型表面活性剂会产生起昙现象，如吐温类，应选E吐温-20。
During my second year of middle school, our teacher gave us a test. I studied hard and __46 well in all the subjects, so the questions were not difficult for me. 47 I stopped when I read the last one：“What is the 48 of the woman that cleans the school?” Of course this was a joke. I saw the cleaning woman every day. She was short and about 60 years old. She had dark hair. But 49 would I know her name? I had never talked __50 her before. In fact, I had never even thought about talking to her. I started to feel rather guilty(惭愧的).Finally, I 51 my paper, without finishing the last question. Before the class ended, one student asked, “Will be last question count(计入) toward __52 grade?” “Of course,” the teacher said, “In your life, you will meet many people. All are important. They deserve(值得) your attention and care, even if you just 53 and say hello to them.” I’ve never forgotten that 54 _. I should get to know all of the people who work and live around me. That was, perhaps, the most 55 lesson of my life. Later, I learned that the cleaning woman’s name was Dorothy.
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