题干

下列事实与胶体无关的是(   )

A:水泥厂和冶金厂常用高压直流电除去大量烟尘,减少对空气的污染

B:将NaCl研磨成直径在1~100nm的颗粒然后分散于水中形成的分散系

C:一束平行光线射入蛋白质溶液里,从侧面可以看到一条光亮的通道

D:氢氧化铁胶体中滴入稀硫酸,先看到红褐色沉淀生成而后沉淀溶解

上一题 下一题 0.0难度 选择题 更新时间:2013-09-07 08:58:20

答案(点此获取答案解析)

B

同类题2

下面文章中有五处需要添加小标题, 请从以下选项(A、B、C、D、E和F)中选出符合各段意思的小标题, 选项中有一项是多余选项。

A.Try to be a small animal doctor

B.Help to clean our city

C.Try to give the disabled a hand

D.Make  more money

E.Visit the old people's home

F.Raise money for poor students

     There are usually some people around us who need help. So it's great to be volunteers. But what can we do? Here are some great ideas.

____

    Not every child can go to school in our country. That's because most of them are too poor to pay for their education. But if we try to raise enough money for these students, they'll be able to finish their schools and have better futures.

____

      The city is our home. However, we pollute it every day. It's time to make it cleaner and greener. We should try to pick up rubbish whenever we see it. We can even go to clean up the city streets, the city parks or the rivers near our city when we are free.

____

      They usually have many problems with their everyday life. An easy thing for a common person may be very difficult for them. Reach out your hands to help to carry their bags, take them to cross the roads. Only a little help can make them feel warm

____

      Many of them have no sons or daughters, so they need someone to spend time with. On weekends or some special days, go to see them. It's a good idea to sing or dance for them. Or just tell them small stories to make them feel less lonely.

____

      They are our friends, but some of them are in danger. We should try to protect and save them. If you are lucky to be their doctor, you'll learn more about how to care for them. And when you see them get better, you'll feel happy and proud.