已知{an}为等差数列，首项与公差均为非负整数，且满足a1+a2＞7a3≥5，则

阅读理解。

     The best way of learning a language is using it. The best way of learning English is talking in English

as much as possible. Sometimes you'll get your words mixed up( 混合 ) and people will not understand

you. Sometimes people will say things too quickly and you can' t understand them. But if you keep your

sense of humor( 幽默感 ) , you can always have a good laugh at the mistakes you make. Don't be

unhappy if  people seem to be laughing at your mistakes. It's better for people to laugh at your mistakes

than to be angry with you , because they don't understand what you are saying. The most important thing

for learning English is : "Don't be afraid of making mistakes because everyone makes mistakes."

1. The writer thinks that the best way for you to learn a language is ____.                       

A. writing  

B. listening  

C. using it  

D. learning grammar

2. What should you do in learning English?

A. Be careful not to make any mistake.  

B. Write as quickly as you can.

C. Laugh more often.      

D. Speak English as much as you can.

3. When people laugh at your mistakes, you should ____.

A. not care                       

B. be happy

C. feel worried                  

D. be unhappy

4. When you make a mistake, you should ____.

A. keep quiet         

B. keep your sense of humor

C. be kind          

D. get angry

5. The story tells us : "_____".

A. Only foolish (愚蠢的) people make mistakes

B. Few people make mistakes

C. People never make mistakes

D. There is no one who doesn't make mistakes

（1）、飞船正常运行时的速度V的表达式及数值；

（2）、飞船在圆轨道上运行的周期T。

患者，男，30岁，曾患肺结核，体检发现口腔黏膜出现蓝黑色素沉着斑片，指缝、乳晕等处也有色素沉着，病因最可能是（）

A.肾上腺皮质功能减退症

B.甲状腺功能亢进症

C.甲状腺功能减退症

D.肢端肥大症

E.Cushing病

自我意识萌芽开始于（）.

A.1岁以内

B.2~3岁

C.1周岁末

D.2周岁末

最佳化