问题 实验题

某学生为了使过滤操作能自动添加液体,设计了“自动加液过滤器”,如下图所示。在倒置的烧瓶中盛放待过滤的液体,液体从“液体流出管”流入漏斗。为使液体顺利流下,还需插入“空气导入管”与大气相通。

(1)“空气导入管”下口应在________,上口应在_______。

A.滤纸边沿下方 B.滤纸边沿上方 C.待过滤液液面上 D.待过滤液中 E.A和B项均可 F.C和D项均可

(2)试简要说明自动加液过滤的原理。

                                                                

答案

(1)A; C

(2)待过滤的液体沿液体流出管流入漏斗,当漏斗里的液面封住“空气导入管”的管口时,空气停止进入烧瓶,液体停止流入漏斗;随着过滤的进行,当漏斗里的液面降到空气导入管的下口以下时,空气又进入烧瓶,液体又流入漏斗。

阅读理解

任务型阅读。根据短文内容,回答问题。

Do you often have a cold, headache or backache? If your answer is yes, your health is a problem. Healthy foods are good for our health. Tofu is a kind of healthy food. It is also a traditional Chinese food. We often eat it in China. Now, many people in other countries think tofu is good for health, too. They also like eating it.

Milk is another kind of healthy food. You should drink one or two glasses of milk every day.

Vegetables are important, too. You should eat lots of them. There are vitamin A, B, C, D, E (维生素A,B,C,D,E) and other vitamins in them.

Of course, it’s important to eat a balanced diet. You need some pork, chicken or beef every day. But you shouldn’t eat much of them.

小题1:Are healthy foods good for your health?

                                                              

小题2:What’s the traditional food in China?

                                                         

小题3:Why are vegetables important to our health?

                                                               

小题4:Which is a good diet: some beef, some pork, a hamburger and a glass of cola for dinner or some pork, tofu and some vegetables?

                                                            

小题5:What did you have for dinner last night?

                                                           

选择题