问题 单项选择题 A1/A2型题

革兰阳性菌和革兰阴性菌细胞壁的共同成分是()

A.磷壁酸

B.脂多糖

C.脂蛋白

D.脂质

E.肽聚糖

答案

参考答案:E

解析:革兰阳性和革兰阴性细菌的细胞壁所共有的成分是肽聚糖,不过前者大约是由50多层的聚糖骨架、四肽侧链和五肽交联桥组成;后者大约由2~3层聚糖骨架和四肽侧链组成。

阅读理解

阅读理解。

     Now I'm studying in the US, I find there are some differences between schools in the US and in

Vietnam.

     One big difference is the clothes students wear at school and how they look. In my country, all the

students should wear uniforms when they go to school. Boys aren't allowed to have long hair. Girls aren't

allowed to have long or colored nails (指甲).

     Another difference is about the rules for parents. In Vietnam, when we begin a new year, our parents

have to go to a meeting in our class. If they don't go to that meeting, their children won't have a grade or

a report card from school.

     However, in the US, there aren't such strict rules above.

     In Vietnam, a class is only 45 minutes and we have only five classes each weekday. When the bell

rings, all the students just sit in their classroom. They can't move to a different room, but students can in

the US.

     In Vietnam, students can't go to work because they can't find a job if they're under 18. But in the

US, many students work after school. This helps them make money. More importantly, this helps them

become more independent. They're able to do things by themselves in their own way, without asking

other people for help.

1. Which country is the writer's hometown?

A. America.          

B. The UK.        

C. China.            

D. Vietnam.

2. What are the girl students allowed to in the writer's country?

A. To have long nails.

B. To color their nails.

C. To grow their hair long.

D. To wears their own clothes.

3. What does the underlined word "independent" mean in Chinese?

A. 勇敢的            

B. 独立的

C. 依赖的            

D. 不礼貌的

4. Which is TRUE about the Vietnamese students according to the passage?

A. They have twenty-five classes a week.

B. They can design their school uniforms.

C. They don't get a report card from school.

D. They can find a job whenever they want.

5. From the passage, we can learn that _____.

A. in Vietnam, the students must sit quietly and can't move around in class

B. the US students don't have such strict rules as the Vietnamese students

C. at the end of a school year, parents in Vietnam have to go to a parents' meeting

D. American parents don't pay for their children's education because they work after school

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