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问题 选择题

已知等腰三角形的周长为16，且一边长为3，则腰长为（　　）

A．3

B．10

C．6.5

D．3或6.5

答案

（1）当3是腰长时，底边为16-3×2=10，

此时3+3=6＜10，不能组成三角形；

（2）当3是底边时，腰长为

1
2
×（16-3）=6.5，

此时3，6.5，6.5三边能够组成三角形．

所以腰长为6.5．

故选C．

写作题

假如你叫大明，收到了你的英国朋友Tony的来信，信中他很关心四川雅安地震后学生的情况。请你根据他的来信内容写一封回信，感谢他对灾区学生的关心，回答他的问题，并谈谈你的感受。

提示词语：thank you, care to， go on， government ，offer，encourage， brave　

Dear Daming,

I’m sorry to hear that a big earthquake happened in Ya’an, Sichuan. Some school buildings broke down in the earthquake and many students couldn’t go to school. But I know the government is trying their best to help them. And Chinese people are so strong and brave that they aren’t afraid of anything difficult. Can the students go on studying now? Please tell me more about them.

I’m looking forward to hearing from you soon.

Yours, 

Tony

Dear Tony,

I’m glad to hear from you.                                         

                                                                                 

                                                                               

                                                                               

                                                                               

                                                                               

                                                                              

Best wishes.  

Yours

Daming
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单项选择题

一般情况下，在密闭的循环水系统中常见的污垢物有（）。

A、腐蚀产物和有机物

B、泥渣和有机物

C、泥渣和腐蚀产物

D、砂粒和微生物群体
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