问题 单项选择题

对固位钉的描述不正确的是()

A.固位钉的数目应根据牙体缺损情况而定

B.自攻螺纹钉遇到一定阻力即于颈部折断

C.固位钉的钉道应大于钉的直往

D.摩擦固位钉的钉道大于钉的直径

E.黏固钉的固位力相对不强

答案

参考答案:D

阅读理解

阅读理解

     More than 10 years ago ,it was difficult to buy a tasty pineapple (菠萝). The fruits that made it to the

UK were green on the outside and , more often than not,hard with an unpleasant taste within. Then in

1996 , the Del Monte Gold pineapple produced in  Hawaii first hit our shelves.    

     The new type of pineapple looked more yellowy-gold than green. It was slightly softer on the outside

and had a lot of juice inside. But the most important thing about this new type of pineapple was that it was

twice as sweet as the hit-and-miss pineapples we had known. In no time, the Del Monte Gold took the

market by storm, rapidly becoming the world's best-selling pineapple variety, and delivering natural levels

of sweetness in the mouth, up until then only found in tinned pineapple.    

     In nutrition it was all good news too.This nice-tasting pineapple contained four times more vitamin C

than the old green variety. Nutritionists said that it was  not only full of vitamins , but also good against

some diseases. People were understandably eager to be able to buy this  wonderful  fruit. The new type

of pineapple was selling fast , and the Del Monte Gold pineapple rapidly became a fixture in the shopping

basket of the healthy eater.    

     Seeing the growing market for its winning pineapple,  Del  Monte tried to keep the market to itself.

But other fruit companies developed similar pineapples. Del Monte turned to law for help, but failed.

Those companies argued successfully that Del Monte's attempts to keep the golden pineapple for itself

were just a way to knock them out of the market.

1. We learn from the text that the new type of pineapple is_________.   

A. green outside and sweet inside    

B.good-looking outside and soft inside    

C. yellowy-gold outside and hard inside    

D.a little soft outside and sweet inside.

2. Why was the new type of pineapple selling well?   

 A. It was rich in nutrition and tasted nice.

B. It was less sweet and good for health.

C. It was developed by Del Monte.

D. It was used as medicine

3. The  underlined  word " fixture" in Paragraph 3 probably refers to something__________.

A. that people enjoy eating    

B. that is always present

C. that is difricult to get        

D. that people use as a gift

4. We learn from the last paragraph that Del Monte __________.

A. allowed other companies to develop pineapples

B. succeeded in keeping the pineapple for itself

C. tried hard to control the pineapple market

D. planned to help the other companies

多项选择题