支气管扩张的病理生理学改变正确的是A．扩张区域肺泡通气量减少，血流正常，通气/血流比
题型：单项选择题
问题：
支气管扩张的病理生理学改变正确的是
A．扩张区域肺泡通气量减少，血流正常，通气/血流比率降低，动-静脉分流，同时肺泡弥散功能障碍，共同导致缺氧
B．限制性为主的混合性通气障碍
C．晚期动脉血气分析多数呈工型呼吸衰竭
D．易早期发生低氧血症
E．很少出现肺动脉高压
题型：单项选择题
| 阅读理解。 | |||
| Saturday morning was bright and fresh. There was a song in every heart, cheer on every face, and a spring in every step. Tom appeared with a bucket of white paint in one hand and a brush in the other. His Aunt Polly told him to paint thefence around the garden. It was thirty yards long and nine feet high. He felt very depressed. | |||
| Then he had a wonderful idea. He picked up his brush and started to work. Soon Ben came along the road. He was happily eating an apple. He stopped to look at Tom. Tom went on painting and pretended(假装)not to see Ben."I'm going swimming," said Ben. "Do you want to go swimming, Tom? But I guess you can't. You have to stay and work, don’t you?" "Work?"Tom said. "This isn't work. I'm enjoying myself. Does a boy get a chance to paint a fence like this every day?" |  | ||
| Ben thought about this. Tom continued painting carefully. Sometimes he stopped, stood back to look at the fence like an artist, and then added a bit more paint in just the right place. Ben was watching Tom paint with great interest. He was getting more and more eager to have a try himself. After a while, Ben asked Tom if he would let him paint a little. Tom thought about it, and said, "No, Ben, I can’t. You see. Aunt Polly wants it to be done well. Aunt Polly said that I must paint it with great care." "Oh, please, Tom," begged Ben. "I can do it. I’ll be really careful. Just let me try. I’ll give you half of my apple. Well, I'll give you all of it!" "Well, all right, Ben," said Tom. "You must be very careful." He gave Ben his brush with worry on his face but joy in his heart.He sat down under the tree,and started to eat Ben’s apple. All day, boys came to make fun of Tom, but they ended up staying to paint. When Ben got tired, Billy was waiting. He gave Tom a kite for a chance to paint. Then Johnny offered him twelve marbles, and so on. By late afternoon Tom had gained all sorts of toys, and the fence had gained three coats of paint. Later Aunt Polly came to look at the painted fence. She was so pleased with Tom’s work that she gave Tom a large cake! | |||
| 1. Why did Tom pretend not to see Ben when he came and watched him painting? | |||
| A. He saw Ben eating an apple happily. B. He tried to make Ben interested in it. C. He didn’t want to go swimming with Ben at all. D. He didn’t want Ben to share the chance to paint the fence. | |||
| 2. What do the underlined words "spring" and "coat" probably mean in the passage according to the given dictionary entries （词条）? | |||
| spring 1 [U,C] the season betw  een winter and summer when plants begin to grow 春天;春季2 [U] the ability of a spring to return to its original position 弹性;弹力 3 [C] a place where water comes naturally to the surface from under the ground 泉 4 [U] a cheerful, lively quality 活力;朝气 coat 1 [C] a piece of clothing with long sleeves that you wear over other clothes when you go outside 外套 2 [C] the fur or hair on an animal’s skin (动物的)皮毛 3 [C] a layer of something such as paint that you put onto a surface 覆盖层;涂层 | |||
| A. 4;3 B. 4;2 C. 3;3 D. 1;3 | |||
| 3. Which of the following is TRUE according to the passage? | |||
| A. Tom gained some toys by helping his friends. B. Tom’s friends often h  elped him paint the fence.C. Tom successfully tricked his friends into painting the fence. D . Billy was the fourth boy to have the chance to paint the fence. | |||
| 4. What do you think of Tom? | |||
| A. He was honest. B. He was smart. C. He was shy. D. He was stubborn. | |||