问题 判断题

轴承合金是制造轴承滚珠的材料。( )

答案

参考答案:

阅读理解

阅读理解。

     Do you get enough sleep? With so much homework it's often difficult to get the rest you need. But you

need to try, because sleep keeps you healthy and it stops you getting fat. Recently, a group of U. S. scientists

did a study (研究) of kids aged between 8 and 13. The study found that if kids sleep for just one extra

(额外的) hour each day, the chance of their getting fat is cut by about 30 percent.

     Why? When people don't get enough sleep, they become tired. When they are tired, they don't exercise

enough. Also, kids like snacks. If they are awake (醒着的) an extra hour or two each day, they have more

time to eat snacks or other unhealthy foods.

     So, how much sleep should you get? Scientists suggest 10 to 11 hours a night for kids aged 5 to 12. For

older kids, eight to nine hours will do.

1. How many reasons are given why people might get fat without enough sleep?

A. 3.

B. 2.

C. l.

D. None.

2. If you are under 10, how long do the scientists advise you to sleep?

A. 10 to 11 hours.

B. 8 to 9 hours.

C. 8 to 13 hours.

D. As long as possible.

3. Where was the study done by the scientists?

A. In China.

B. In Britain.

C. In America.

D. In Japan.

4. What does "eight to nine hours will do" mean? 

A. Eight to nine hours' sleep will be good and enough.

B. Eight to nine hours' sleep will be too long.

C. Eight to nine hours' sleep will help get fat.

D. Eight to nine hours' sleep will help eat snacks and unhealthy foods.

5. What does the passage talk about?

A. How to get long sleep.

B. How to keep fat.

C. Enough sleep makes people healthy and slim (苗条).

D. Long sleep makes people healthy and slim.

实验题

(13分)实验室利用右图所示装置制取乙酸异戊酯,其合成过程为:

①向圆底烧瓶中加入几粒碎瓷片,并注入0.14mol异戊醇和0.35mol冰醋酸,再加入4 mL浓H2SO4至不再分层。

②在烧瓶上安装冷凝回流装置,加热混合物1小时后,冷却至室温。

③把混合物转至分液漏斗中,加少量蒸馏水,振荡分层后除去水层,再用蒸馏水洗涤有机层。

④用5%的NaHCO3溶液分几次洗涤产品直至中性。

⑤向上述溶液中加NaCl晶体,搅拌静置,对液体进行分液。

⑥将粗产品转至蒸馏烧瓶中,加入碎瓷片,并加适量无水MgSO4或Mg(NO3)2蒸馏,收集135 ℃—143 ℃之间的馏分。

试完成下列问题:

(1)冷凝管中冷却水流向是由_____________进入,由____________流出。(填“A”或“B”)

(2)圆底烧瓶中的物质_______________(填“会”或“不会”)从冷凝管上口跑掉,是因为

_____________________________________________________________________________。

(3)合成实验中浓H2SO4的作用是____________________________________________,碎瓷片的作用是__________________________________________________________________。

(4)乙酸与异戊醇的物质的量之比0.35∶0.14>1∶1的原因是_______________________。

(5)在③中用蒸馏水多次洗涤的作用是_______________________________________。④中用NaHCO3溶液洗涤产品的作用是________________________________________________。