问题 问答题 简答题

糊制书封壳应使用什么胶黏剂,为什么?

答案

参考答案:

糊制书封壳所用的胶黏剂是水分少、干燥快、定型好的骨胶或合成树脂胶中的聚乙烯醇(PVA.胶黏剂。因为这类胶黏剂属热性胶,受湿度控制较敏感,不易产生快速的渗透能力,便于完成黏结定型,因此书封壳糊制后不会因胶黏剂水分大量向纸张中渗入而产生书封壳干燥后的翘曲变形。

阅读理解

阅读理解。

     If' you have a chance to travel in Europe, you'd better choose Italy as a good place to visit, because

Italy is a very famous country with a long history, and there are many interesting cities in this country.

There are three million people each year that visit Pisa. It's known for the Leaning Tower of Pisa.

     The tower looks as if  it might fall at any time. In fact, some visitors stop at the tower just long enough

to take a picture, then they hurry away. The tower has 294 steps. Visitors who can climb to the top and

come down will feel like heroes.

     Engineers say that the visitors are safe, though the tower cloes lean. This tower has been leaning for

about eight hundred years. And it leans a tiny (微小的) bit rnore every year."If this keeps on. the tower

will fall at last. But many engineers are trying their best to keep the tower standing as long as possible.

根据短文内容,回答下列问题。

1. Why would people like to visit Italy, if they have a chance to travel in Europe?

    ______________________________________________________________________________

2. What's the reason that people are interested in Pisa?

    ______________________________________________________________________________

3. What do you think will happen to the people who are standing near the tower?

    ______________________________________________________________________________

4. When did the tower begin to lean?

    ______________________________________________________________________________

5. Will the tower fall? Why or why not?

    ______________________________________________________________________________

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