问题 单项选择题

男性,40岁,体健,吸烟:40支/日。临床诊断为慢性牙周炎,经牙周系统治疗及局部药物治疗后效果不理想,口腔卫生状况尚可。应最先考虑影响其疗效的因素是()

A.营养因素

B.咬合关系

C.吸烟

D.使用的药物不当

E.工作紧张

答案

参考答案:C

解析:试题难度:难,此题考点为考查牙周疾病的危险因素。牙周治疗效果不佳的原因很多,口腔卫生控制不佳是其中的主要因素,但该患者的口腔卫生状况不差,因此主要考虑其他方面的因素,该患者存在一个明显的危险因素即吸烟,且吸烟量很大,吸烟既影响牙周疾病的发病和病情程度,又影响牙周治疗效果,因此正确答案为C。备选答案中的其他方面在题干中并未给出相应信息。

选择题
阅读理解

  The plan: turn Mars into a blue world with streams and green fields, and then fill it with creatures (生物) from the earth. This idea may sound like something from a science fiction (科幻小说), but it is actually being taken seriously by many researchers.

  This suggested future for the “red planet” will be the main topic for discussion at an international conference hosted by NASA (美国宇航局) this week. Leading researchers as well as science fiction writers will attend the event. It comes as NASA is preparing a multibilliondollar Mars research programme. “Turning Mars into a little earth has long been a topic in science fiction,”said Dr Michael Meyer, NASA’s senior scientist for astrobiology (太空生物学). “Now, with scientists exploring the reality, we can ask what are the real possibilities of changing Mars.”

Most scientists agree that Mars could be turned into a little earth, although much time and money would be needed to achieve this goal.

  But many experts are shocked by the idea. “We are destroying our own world at an unbelievable speed and now we are talking about ruining another planet,” said Paul Murdin, of the Institute of Astronomy, Cambridge, UK. Over the past months, scientists have become increasingly confident they will find Martian life forms. Europe and America’s robot explorers have found proof that water, mixed with soil, exists in large amounts on the planet.

In addition, two different groups of scientists announced on March 28 that they had found signs of methane (甲烷) in the Martian atmosphere (大气). The gas is a waste product of living creatures and could be produced by microbes (微生物) living in the red planet’s soil.

  But scientists such as Dr Lisa Pratt, a biologist at Indiana University, say that these microbes will be put in danger by the little earth project. “Before we have even discovered if there is life on Mars, we are talking about carrying out projects that would destroy all these native lifeforms, all the strange microbes that we hope to find buried in the soil,” said Dr Pratt. This view is shared by Monica Grady, a planetary scientist at the Natural History Museum, London. “We cannot risk starting a global experiment that would wipe out the precious information we are looking for.” she said, “This is just wrong.”

5. The passage is about________.

A. a plan turning Mars into a little earth

B. the necessity of changing Mars

C. Mars supporting life

D. finding water in the Mars

6. Which of the following is NOT the reason why some scientists are against the plan?

A. The project would wipe out all the native lifeforms on the Mars.

B. The project will cost too much money and work.

C. We would ruin Mars.

D. We are destroying our own world at an unbelievable speed. 

7. We can infer from the passage that________.

A. water is a crucial factor for life

B. the project will have little effect on the native lifeforms supposed to live on the Mars

C. Monica Grady is in favour of carrying out the little earth project

D. the idea turning Mars into a little earth is nothing but a science fiction

8. Which of the following supports the conclusion of microbes living in the Mars’s soil?

A. Scientists found liquid water in the Mars.

B. Scientists found signs of methane in the Martian atmosphere.

C. Scientists found a lot of good soil on the Mars.

D. Scientists found some creatures living on the Mars.