问题 填空题

(1)白色衣服上如果有铁锈痕迹,应该用下列物质中的______进行处理后,再用清水冲洗.

A.汽油、B.洗衣粉、C.白醋、D.红醋.

(2)酒厂用发酵法生产白酒时,需要加入适量硫酸来控制酸度,发酵完成后进行蒸馏,即得到白酒,但不能用盐酸代替硫酸,其原因是______.

(3)在焊接和电镀金属时,常用稀盐酸,其作用是______.

答案

(1)根据铁锈主要成分氧化铁能与酸发生反应,应选取醋酸来处理衣服上的铁锈;又衣服为白色,选用红醋会沾染衣服.

故选C

(2)“发酵完成后进行蒸馏”的过程是:对发酵后所得液体进行蒸发,然后对蒸发出来的蒸气进行冷却降温,使之变成液体.如果蒸气中混有其他气体,得到的酒精将混有杂质.

故答:蒸馏时盐酸中的HCl蒸气会混入酒精中.

(3)铁锈会影响焊接的牢固度,因此在焊接前应进行除锈.

故答:溶解铁制品表面的铁锈.

阅读理解

阅读理解。

    

     Which animal do you think is "the king of the animals", the elephant, the lion or the tiger? They are all

large and strong. But I think the tiger is "the king of the animals". If you watch carefully, you

can find some black lines on the tiger's forehead (前额). The lines look like the Chinese word "WANG".

The word means "the king of the world" in Chinese.

     Most of the tigers come from China and India. Tigers are dangerous animals. They look scary

(吓人的). They like eating meat. They have yellow fur with black lines. They usually weigh about 200

to 300kg. Tigers can run fast. They run at a speed of 20 meters per second.

     Some people think they are dangerous. But they don't know tigers are in danger now. There are only

20 to 30 wild South China Tigers in China and less than 300 in the world. Lots of people kill them for

their fur. We should take action to protect them.

1. Which animal does the writer think is "the king of the animals" ?

A. The elephant.              

B. The lion.

C. The tiger.                  

D. The lion and the tiger.

2. Some black lines on the tiger's forehead look like______.

A. 王      

B. 汪      

C. 主      

D. 丰

3. Which of the following is NOT true according to the passage?

A. Tigers like eating meat.

B. All of the tigers come from China.

C. Tigers usually weigh about 200 to 300 kg.

D. Tigers can run at a speed of 20 meters per second.

4. How many wild South China Tigers are there in China?

A. There are less than 20.

B. There are only 20 to 30.

C. There are less than 200.

D. There are less than 300.

5. Why do you think the tigers are in danger?

A. Because the tigers couldn't find enough food to eat.

B. Because lots of people kill them for their safety.

C. Because lots of people think they are dangerous.

D. Because lots of people kill them for their fur.

多项选择题