题目内容

25．对胶体具有保护作用的是（）

A. 蔗糖
B. 明胶
C. 氨水
D. 生理盐水
E. 硫酸钾

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26．下列不能使溶胶聚沉的方法为 ( )

A. 加入电解质
B. 加入带相反电荷的胶体
C. 加热
D. 加入溶剂

1.— I called you at 4:00 yesterday afternoon, but no one answered. — Sorry, I _____ with my friends at that time.

A. swim
B. swam
C. will swim
D. was swimming

2.— Excuse me, where is Mr. Brown's office?— Sorry, I don't know. I _____ here for only a few days.

A. work
B. worked
C. have worked
D. will work

3.—Where is Bob?— He ______ to Harbin for a meeting.

A. went
B. has been
C. has gone
D. had gone