How would you like to mail it?（）
A. Thank you very much.
B. Post office is over there.
C. I'll be coming.
D. By air mail, please.
查看答案
自然人客户信用为（）级为较好等级。
A. BB
B. AAA
C. AA
D. A
E. BBB
粒径在（）之间属于胶体和悬浮物的过渡阶段。
A. 100nm-1m
B. 300nm-2m
C. 500nm-5m
D. 1000nm-5m
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