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问题 单项选择题

关于DNA二级结构，描述错误的是

A．两条DNA链走向相反
B．碱基配对是A与U，G与C
C．两条链皆为右手螺旋
D．双螺旋每周10对碱基
E．碱基对之间形成氢键

答案

参考答案：B

阅读理解

阅读理解。

Dear Li Ming,    

        Now we are on the farm of our village in the west of England.We are having a good time.There are

many children here.Mary and Ted are playing soccer.Some people are singing under the big green tree.

Some people are swimming in the river.Some people are taking photos near the river.I'm writing to you.

What are you doing now? I hope you are enjoying the summer  holiday(假期)。       

                                                                                                                             Mike

1. Who is writing the letter?[ ]

A. Li Ming.      

B. Lucy.        

C. Mike.          

D. Kate.

2. Where are Mike and his friends?[ ]

A. On a farm.  

B. In the west of China.  

C. In a city.    

D. In the south of England.

3. What is Ted doing?[ ]

A. He's reading.    

B. He's taking photos.

C. He's singing.    

D. He's playing soccer.

4. What are Mike and his friends doing?[ ]

A. They are enjoying the holiday.    

B. They are studying.

C. They are swimming and singing  

D. They are working.

5.  What holiday are they having?[ ]

A. A summer holiday.    

B. A winter holiday.
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单项选择题

细分市场的评估和目标市场的选择是对品牌从（）多维定位。

A.产品角度、消费者角度或竞争者角度

B.市场角度、产品角度或消费者角度

C.产品角度、消费者角度或客户角度

D.产品角度、客户角度或竞争者角度
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