问题 选择题

如图所示,小试管中盛有几毫升水,与大试管连通的U形细玻管内放有少量的水(已染成红色)。如沿小试管壁小心地慢慢注入3 mL浓硫酸,静置片刻后,U形细玻管中可观察到的液面现象是(   )

图4-14

A.左高右低

B.左低右高

C.左右一样高

D.来回振动

答案

答案:B

浓硫酸与少量的水接触后立即放出大量的热,使整个密闭系统的温度升高,压强增大,U形管中液柱被压向右侧,液面左低右高。

阅读理解

阅读理解。

       Do you drink milk every day? Milk is good for health. It is one of the healthiest foods. But do

you know the best ways to drink milk? Here are some suggestions.    

       ◆ You should not drink milk on an empty stomach.  Milk is not enough for a meal in itself. You

need other foods with the milk, like bread and biscuits.  They help you to take in more of the milk's

nutrients (营养).    

       ◆ If there's no milk, soybean milk (豆浆) is a good choice.  People drink milk because it gives the

body calcium (钙).  So you can try foods with lots of calcium,  these could be bean products, like tofu,

nuts, or shrimp (虾).    

       ◆ When is the best time for a glass of milk? At breakfast or an hour or two before dinner. Milk

helps you sleep. You can have a glass before you go to bed.    

       ◆ Iced milk may taste good, especially in summer.  But it may not be good for your health.  Iced

milk gives your body less calcium.

1. We should drink milk with               .          

A. other drinks                    

B. some fruits          

C. other foods                      

D. some vegetables

2.              is also a kind of food with lots of calcium.        

A. Soybean milk  

B. Rice            

C. Apples        

D. Bread

3. If you want to sleep well, you can have                 before going to bed.        

A. some nuts                        

B. some tofu        

C. a glass of milk                    

D. a glass of soybean milk

4. Hot milk gives our body              iced one.          

A. as little as calcium                  

B. more calcium than          

C. less calcium than                  

D. as much calcium as

5. The passage tells us                .          

A. the advantages to drink milk        

B. there are many healthy foods          

C. the nutrients in milk                

D. the best ways to drink milk

单项选择题