问题 名词解释

预热成型工艺

答案

参考答案:

与上述热压成型工艺不同,该工艺采用在原料进入成型机压缩之前,对其进行了与热处理,即将原料加热到一定温度,使木素软化起粘结作用,并且在后续压缩过程中减少原料与模具的摩擦作用,降低成型压力,从而提高成型部件的使用寿命,降低能耗。

单项选择题
单项选择题

Time spent in a bookshop can be most enjoyable, whether you are a book-lover or merely there to buy a book as a present. You may even have entered the shop just to find shelter from a sudden shower. But the desire to pick up a book with an attractive dust-jacket is irresistible. You soon become absorbed in some book or other, and usually it is only much later that you realize that you have spent far too much time there.

This opportunity to escape the realities of everyday life is, I think, the main attraction of a bookshop. There are not many places where it is possible to do this. A music shop is very much like a bookshop. You can wander round such places to your heart’s content. If it is a good shop, no assistant will approach you with the inevitable greeting: "Can I help you, sir" You needn’t buy anything you don’t want. In a bookshop an assistant should remain in the background until you have finished browsing. Then, and only then, are his services necessary.

You have to be careful not to be attracted by the variety of books in a bookshop. It is very easy to enter the shop looking for a book on, say, ancient coins and to come out carrying a copy of the latest best-selling novel and perhaps a book about brass-rubbing -- something which had only vaguely interested you up till then. This volume on the subject, however, happened to be so well illustrated and the part of the text you read proved so interesting that you just had to buy it. This sort of thing can be very dangerous. Booksellers must be both long suffering and indulgent.

There is a story which wei1 illustrates this. A medical student had to read a textbook which was far too expensive for him to buy. He couldn’t obtain it from the library and the only copy he could find was in his bookshop. Every afternoon, therefore, he would go along to the shop and read a little of the book at a time. One day, however, he was dismayed to find the book missing from its usual place and about to leave when he noticed the owner of the shop beckoning to him. Expecting to be reproached, he went toward him. To his surprise, the owner pointed to the book, which was tucked away in a corner. "I put it there in case anyone was tempted to buy it," he said, and left the delighted student to continue his reading.

The textbook the medical student was interested in was tucked away in a corner()

A. to prevent anyone from buying it

B. because the medical student might take it away

C. in case the medical student was tempted to buy it

D. because it was a rare and expensive book