问题 问答题

小丽同学按以下步骤对她所用的牙膏进行探究:

[资料]牙膏中常用氢氧化铝、碳酸钙等物质作摩擦剂.请回答:

(1)你认为用作牙膏摩擦剂的物质应具备什么特点呢?(回答一条即可)______

(2)小丽选择的试剂X是______.

A.紫色石蕊试液          B.pH试纸          C.酚酞试液

(3)从探究过程来看,小丽可检验出摩擦剂中一定存在的物质是______.

答案

(1)作为摩擦剂来使用颗粒不能太大,否则会磨损牙齿.

(2)测得pH值为整数,可以知道应该是选择的pH试纸来测定的.

(3)根据提示资料及沉淀与盐酸反应生成了气体,可以确定在牙膏中含有碳酸钙.

故本题答案为:(1)细小的粉末状固体

(2)B

(3)CaCO3

阅读理解

When I was small and my grandmother died, I couldn't understand why I had no tears. But that night when my dad tried to cheer me up, my laughs turned into crying.

So it came as no surprise to learn that researchers believe crying and laughing are controlled by the same part of the brain. Just as laughing has many health advantages, scientists are discovering that so does crying.

Whatever helps us to reduce pressure is important to our emotional health, and crying seems to work well. One study found that 85 percent of women and 73 percent of men report feeling better after crying.

Besides, tears attract help from other people. Researchers agree that when we cry, people around us become kinder and friendlier and they are more ready to provide support and comfort. Tears also enable us to understand our emotions better; sometimes we don't even know we're very sad until we cry. We learn about our emotions through crying, and then we can deal with them.

Just as crying can be healthy, not crying---holding back tears of anger, pain or suffering---can be bad for physical health. Studies have shown that too much control of emotions can 1ead to high blood pressure, heart problems and some other illness. If you have a health problem, doctors will certainly not ask you to cry. But when you feel like crying, don't fight it. It's a natural, healthy and emotional response.

小题1:Why didn't the author cry when her grandmother died?

A.Because her father did not want her to feel too sad.

B.Because she did not love her grandmother.

C.Because she was too shy to cry at that time.

D.The author doesn't give the explanation.小题2:It can be inferred from the text that _______________________.

A.there are two ways to keep healthy

B.emotional health has a close relationship to physical health

C.crying and laughing play the same roles

D.crying does more good to health than laughing小题3:According to the author, which of the following statements is true?

A.Crying is the best way to get help from others.

B.Fighting back tears may cause some health problems.

C.We will never know our deep feelings unless we cry.

D.We must cry if we want to reduce pressure小题4:What might be the most suitable title for the text?

A.Why We Cry

B.How to Keep Healthy

C.Power of Tears

D.New Scientific Discovery小题5:What is the author's attitude to "crying"?

A.Positive.

B.Negative.

C.Touched.

D.Upset.

单项选择题