问题 选择题

某人在常温下作平静呼吸时,吸气刚结束的瞬间与呼气刚结束的瞬间相比(  )

A.肺内气压相同

B.肺内气体总体积相同

C.气体温度、湿度相同

D.肺内氧气总质量相同

答案

当肋间肌和膈肌收缩时,胸廓体积增大,肺也随之扩张,肺内气压低于外界大气压,外界气体通过呼吸道进入肺,完成吸气;当肋间肌和膈肌舒张时,胸廓体积缩小,肺也随之回缩,肺内气压高于外界大气压,肺内气体通过呼吸道排出体外,完成呼气;吸气刚结束的瞬间与呼气刚结束的瞬间,肺内气压与外界大气压相等,此时人体既不呼气也不吸气.

故选A

阅读理解

阅读理解

                                                                  Peanuts to This

     Proudly reading my words, I glanced around the room, only to find my classmates bearing big smiles

on their faces and tears in their eyes. Confused, I glanced toward my stone-faced teacher. Having no

choice, I slowly raised the report I had slaved over, hoping to hide myself. "What could be causing

everyone to act this way?"

     Quickly, I flashed back to the day Miss Lancelot gave me the task. This was the first real talk I

received in my new school. It seemed simple: go on the Internet and find information about a man named

George Washington. Since my idea of history came from an ancient teacher in my home country, I had

never heard of that name before. As I searched the name of this fellow, it became evident that there were

two people bearing the same name who looked completely different! One invented hundreds of uses for

peanuts, while the other led some sort of army across America. I stared at the screen, wondering which

one my teacher meant. I called my grandfather for a golden piece of advice; flip (掷) a coin. Heads-the

commander, and tails-the peanuts guy. Ah! Tails, my report would be about the great man who invented

peanut butter, George Washington Carver.

     Weeks later, standing before this unfriendly mass, I was totally lost. Oh well, I lowered the paper and

sat down at my desk, burning to find out what I had done wrong. As a classmate began his report, it all

became clear, "My report is on George Washington, the man who started the American Revolution." The whole world became quite! How could I know that she meant that George Washington?

     Obviously, my grade was awful. Heartbroken but fearless, I decided to turn this around. I talked to

Miss Lancelot, but she insisted: No re-dos; no new grade. I felt that the punishment was not justified, and

I believed I deserved a second chance. Consequently, I threw myself heartily into my work for the rest

of the school year. Ten months later, that chance unfolded as I found myself sitting in the headmaster's

office with my grandfather, now having an entirely different conversation. I smiled and flashed back to the

embarrassing moment at the beginning of the year as the headmaster informed me of my option to skip

the sixth grade. Justice is sweet!

1. What did the author's classmates think about his report?

A. Controversial.                  

B. Ridiculous.

C. Boring.                        

D. Puzzling.

2. Why was the author confused about the task?

A. He was unfamiliar with American history.

B. He followed the advice and flipped a coin.

C. He forgot his teacher's instruction.

D. He was new at the school.

3. The underlined word "burning" in Para. 3 probably means _______.

A. annoyed                      

B. ashamed

C. ready                        

D. eager

4. In the end, the author turned things around _______.

A. by redoing his task

B. through his own efforts

C. with the help of his grandfather

D. under the guidance of his headmaster

选择题