混凝剂对水中的胶体粒子的作用有三种，其中主要使胶粒脱稳作用的是（）
A.吸附
B.粒间架桥
C.网捕
D.电中和
参考答案：D
铜制品要用肥皂和水清洗，无需擦干，自然风干即可。（）
I'm tired out. I() all afternoon and I don't seem to have finished anything.
A. shopped
B. have shopped
C. had shopped
D. have been shopping
