问题
单项选择题
对聚合物溶液初始粘度的影响上，相同质量含量时，（）的降粘作用最大。
A、Cu2+
B、Mg2+
C、Al3+
D、Fe3+
答案
参考答案：C
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对聚合物溶液初始粘度的影响上，相同质量含量时，（）的降粘作用最大。
A、Cu2+
B、Mg2+
C、Al3+
D、Fe3+
参考答案：C
| 从方框中选出适当的句子补全对话，其中有两项是多余的。 | |
| A: Lucy, why are you going out 1 ? B: That's the sound of a truck collecting rubbish. A: Do you mean you have to take the rubbish to the truck? B: Yes. You know 2 is our duty. We should help protect the environment. A: I agree. 3 , we must do something around the neighbourhood. B: Sure. It is our duty to keep the environment clean and tidy. If we make a contribution to protecting the environment, 4 A: That's right. We mush try our best to make our country more beautiful. So we should 5 to improve the environment.
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