问题 选择题

在意外事故中,动脉损伤远比静脉损伤危险,这是因为动脉中的血液(  )

A.无废物和二氧化碳

B.含有更多的白细胞和抗体

C.含有更多的养料和氧气

D.具有较大的压力,常会喷射而出

答案

血管分为动脉、静脉和毛细血管三类.动脉将血液从心脏运到全身各处,血管壁比较厚,弹性大,血液流速快,压力大;静脉将血液从全身各处运到心脏,血管壁比较薄,弹性小,血液流速较慢;毛细血管是连接最小的动脉和静脉之间的小血管,此类血管壁最薄,只有一层上皮细胞组成,腔最细,只允许红细胞单行通过,流速极慢,利于进行物质交换.

由于动脉血管内血液流速快,压力大,出血时血呈喷射状喷出,危险极大.

故选D

单项选择题
阅读理解

阅读理解

     In a world where comparisons happen non-stop, it is difficult to look outside yourself and to

ever be content with who you are. There's always someone who's a bit better. The only solution

is to reach inside and measure against what Warren Buffett calls your own inner yardstick. There

is no more accurate measure for comparison than who you were yesterday, last week or last

decade, when you were at your best.

     Nothing useful ever comes from comparison to others. Either you see yourself as better than

someone and you get lazy, or you see someone else as better than you and you feel like all your

hard work is for nothing. It is a fool's game. None of us are inherently above or below the person

next to us. We are who we are. Not one of us is exactly alike. The only direct and honest

comparison is within yourself. Everything else is apples to oranges.

     My opinion is that you are only allowed to compare yourself to someone else if their life situation

is the same as your own. Good luck finding that match. And one thing is for sure. No matter how

hard you work and how dedicated you are, there will always be someone who can run a little faster,

jump a little higher, score a little better or look a little nicer in a swimsuit. And if there's not, you can

bet someone is coming up fast behind you. So how can you always win in life? Become your best

competitor.

     The following are the reasons why you are your own best competitor.

     1. You will always be motivated.

     Having an image of your most recent past limits is the perfect thing to push you to the next level.

If you ran 7 flights of stairs yesterday, then do 8 today. Who cares if the guy next to you did 15? It

doesn't make a bit of difference. You are a more fit person today than you were yesterday. Your

own progress is all you need.

     2 . You will continuously be your personal best.

     If you commit to a slightly higher standard of yourself every day, you will always be at the top of your game. And that game will only get better. But if for some reason you fall off your mark, you will always have the past image of your best performance to show you what you're capable of. Once you've lone it, you know what's possible and then it's just a matter of doing it again.

 1. Through the passage the writer advises the readers to ____.

A. avoid comparison with others

B. work much harder

C. pay attention to others' progress

D. make full use of motivation

 2. If you want to achieve your best, according to the author, you should ____.

A. see yourself better than others

B. measure accurately

C. compare with yourself

D. be honest with yourself

3. Which of the following is certain to happen according to the author?

A. Finding someone else who is in the same life situation as you are.

B. Finding someone who runs faster and jumps higher than you.

C. Finding someone who is hiding right behind you.

D. Finding someone who almost always wins in their life.

4. What can help you up to higher level in your life according to the passage?

A. Comparing yourself with the guy next to you.

B. Thinking about your own progress.

C. Promising to play a game every day.