问题 问答题 简答题

什么是橡胶制品的老化?其保管保养应注意的事项是什么?

答案

参考答案:

橡胶制品由于受周围环境条件如空气、阳光和热的作用,其化学结构受到破坏,物理性能改变,机械性能降低,变硬、脆或软粘,不再适用于应用的现象叫做老化。

橡胶及制品在储存方面有一定共性,一般要求库温-15~40℃,相对湿度50%~80%,阴凉,通风、忌受潮,避免阳光直射与雨淋,距离热源应在2米以上。勿与溶剂类、油类、酸、碱类接触,堆码不宜过高,并应定期倒垛。

阅读理解

阅读短文,选择正确答案。

     Some members of an International Voluntary Organization (国际志愿组织) arrived at a small village of an

African country. 

     The villagers lived in small houses, which were built with wood and leaves. There was no school or hospital.

The villagers didn't know how to grow crops. They only went to kill some wild animals and pick some fruits in

the mountains as their food. The volunteers (志愿者) came here to help the village kids. They brought with them

many textbooks and some medicine. They taught the kids how to play volleyball and also tried to learn their

language so that they could talk with the kids better. 

     Because of their hard work, the International Voluntary Organization gave the villagers the money to carry

electricity to the village. When the lights in every house were shining, the villagers were very excited. They called

them "the little suns". Then, they held a party to choose some lucky men who would invite the volunteers to go

to their homes to see the beautiful night together with their families.

1. The volunteers came to the small village ________. [ ]

A. for fun

B. to help the villagers

C. for a trip

D. to do some experiments

2. How did the villagers get their food? [ ]

A. They grew crops.

B. Someone sent them the food.

C. They got it from the river.

D. They looked for it in the mountains by themselves.

3. The volunteers tried to learn their language because ________. [ ]

A. it was great fun

B. they thought it was interesting

C. they wanted to talk with the kids better

D. they wanted to learn this kind of language

4. Before the volunteers came to the village, there was ________. [ ]

A. no electricity in the village

B. only a school in the village

C. no food for the village

D. a hospital in the village

5. The lucky men could ________. [ ]

A. turn on the lights first

B. carry electricity to the village

C. be offered some money to carry electricity

D. have a chance to invite the visitors to go to their homes

单项选择题