问题 单项选择题 A1/A2型题

有关咖啡因的作用错误的是()

A.小剂量减轻疲劳,振奋精神

B.舒张支气管平滑肌,且能利尿

C.较大剂量可直接兴奋延脑呼吸中枢与血管运动中枢

D.治疗剂量兴奋脊髓

E.可直接兴奋心脏,扩张冠状血管

答案

参考答案:D

解析:咖啡因的中枢作用较强,可兴奋心脏、扩张血管,有直接和间接作用,取决于用药时间、剂量、用药史等,小剂量对大脑皮质有选择性兴奋作用,可减轻疲劳,振奋精神;较大剂量可直接兴奋延脑呼吸中枢与血管运动中枢,另外还能舒张胆道和支气管平滑肌、利尿及刺激胃酸分泌;不良反应较轻,中毒剂量会兴奋脊髓,所以答案为D。

阅读理解

Do you want to know anything about ma staying in America? Well, Let me tell you the truth, it is really an eye-opening experience to study here.

In China, I had English classes five times a week since the fifth grade. However didn’t know textbook English was very different from everyday English until I came to Hotchkiss School, Connecticut.

When I first studied English, I was told to say,“I am fine” when people say “How are you?”But in the US, I found that people say,” I am good” or “I am tired.”

One day, someone greeted me with” What’s up?”It made me confused. I thought for a moment and then smiled because I didn’t know what to say.

Since then, I have discovered more and more differences between Chinese and the US cultures.

To my surprise, the US girls spend a lot of time in burning sun getting a tan (晒黑). However, in China, girls try every possible way to get their skin paler(白的).

I am also surprised by how hardworking the US students are. In China, schoolwork is almost everything, so we study hard all the time. But here, an “excellent” student gets good grades, does a lot for the public and plays sports or music .The kids here are so talented ,I am starting to be sorry that I gave up playing the piano at an early age and that I have never thought about sports.

小题1: How often did the writer have an English class in Grade Five?

A. Four times a week.

B. Five times a week.

C. Six times a week.

小题2:To the winter, textbook English is          everyday English.

A. quite different from B. the same as   C. easier than

小题3:A good US student spends his/her time         .

A. only in doing homework 

B. only on sports or music

C. on studies, sports or music and public work

小题4:Which of following is NOT true?             

A. The writer is now in the US

B. American girls love to have while skin

C. The US students are talented and hard working.

小题5:Which is the best title for the passage?           

A. My own Travel in the US.

B. My Study in the US.

C. My friends in the US.

单项选择题