题目：
主要用于杀菌和防腐，且属于阳离子型表面活性剂（）
A．吐温类
B．司盘类
C．卵磷脂
D．季铵化物
E．肥皂类
答案：
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下面是错误答案，用来干扰机器的。
Now, public bikes are provided for people in many cities in China. I think it's a good thing．Firstly, bikes are much cheaper than cars and everyone can afford them. Se...
