问题 单项选择题

用牙钳拔牙时,下列描述中错误的是

A.扭转力适用于单个锥形根的牙

B.摇动力适用于扁根或多个牙

C.摇动时首先向阻力小的一侧进行

D.牵引力不能与扭转力等结合使用

E.钳喙应尽量向根方夹持

答案

参考答案:D

解析:拔圆形根牙时可使用扭转力,而所有拔除脱位时,均使用牵引力。

单项选择题
阅读理解

阅读理解

    A university math tutor has discovered the science behind "singledom",finding that our chances of finding

the perfect partner are just 1 in 285,000.Peter Backus,a tutor at the University of Warwick,published his

"Why I Don't Have a Girlfriend" paper after a threeyear love drought.

    His unconventional study uses a famous math formula called The Drake Equation (德雷克等式),which

was first used to estimate the existence of extraterrestrial (地球以外) life.

    The results don't look promising for British singles.30yearold Mr Backus found that out of the 30 million

women in the UK,only 26 would be suitable girlfriends for him.

    The dull equation takes into account the number of  women aged  24  to 34, living in his home city of

London,and who are single,meaning his chances of meeting his dream woman on a night out are slim.

    The economics expert said: " There are  26 women in London with whom I  might have a wonderful

relationship.So, on a given night out in London there is a 0.0000034%  chance of meeting one of  these

special people.That's a 1 in 285,000 chance,so it's not great."

    The puzzling Drake equation reads: N=R* x Fp x Ne x Fi x Fc x L,and helped pioneering scientist

Professor Drake to predict that there could be 10,000 civilizations in our galaxy.

    Mr Backus simply replaced the original equation with his own criteria for a dream date,which included

the percentage of women likely to find him attractive,and the number of girls aged 24~34 in London.He

said:"The research may sound depressing to people looking for love,but the_good_news_for_singles is,it's

probably not your fault!"

1.Mr Backus' discovery in this passage is mainly concerned about________.

A.whether there exists life out of our planet

B.the possibility of his being able to find love

C.how to get rid of singledom

D.what math can do to serve our daily life

2.What does Mr Backus think of the result of his research?

A.Optimistic.  

B.Depressing.  

C.Unrealistic.  

D.Exciting.

3.What can we learn from the first paragraph?

A.Mr Backus' major research field is "singledom".

B.Mr Backus found a girlfriend three years ago.

C.Mr Backus' new thesis will surely be well received.

D.Mr Backus has been searching for love for long.

4.By "the good news for singles" in the last sentence,Mr Backus probably mean________.

A.you don't have to blame yourself for remaining single

B.maybe the discovery is not reliable at all

C.the result was based on his own criteria

D.there might be more dream date out of London

5.Which of the following statements is true?

A.This passage could be published in a scientific magazine.

B.The passage intends to prove there are other civilizations.

C.The writer doesn't really understand the Drake equation.

D.Most women in London are not suitable for university teachers.