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问题 单项选择题

钢材牌号Q235，Q345，Q390的命名是根据材料的( )。

A．设计强度
B．标准强度
C．屈服点
D．含碳量

答案

参考答案：C

选择题

将2．5 mol A和1．25 mol B通入容积为1L的真空密闭容器中，经5s达到平衡状态。3A(g)＋B(g)pC(g)＋2D(g)，生成0．5 mol D，又知C的平均反应速率是0．1 mol/(L·s)，则下列说法中正确的是

①A的转化率为20%　②B的转化率为25%　③A的平均反应速率为0．1mol/(L·s)　④方程式中p＝2　⑤B的平均反应速率为0．05mol/(L·s)

A．①②

B．②③

C．③④

D．④⑤
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书面表达。
     根据中文提示和英文书信内容，写一封意思连贯、符合逻辑、不少于60词的回信，信的开头和结
尾已给出，其词数不计入所完成的回信内。请不要写出你的校名和姓名。
     假设你叫李平，是美国中学生斯蒂文的笔友，你收到了他的来信。请给斯蒂文写一封回信。根据
中国人的性格特点和风俗习惯，告诉他在中国家庭居住时应注意些什么。 
Dear Li Ping,
     I'm going to China in September. I'll study in No.1 Middle School in Beijing for half a year.
And I'll live in a home of a Chinese student. I've never been to China and I know very little
about Chinese families. Can you tell me something about it so that I can get on well with them?
     I'm looking forward to hearing from you.
                                                                                                                         Yours,
                                                                                                                         Steven

Dear Steven,
     I'm glad to hear that you will come to China soon. _______________________________
___________________________________________________________________________
___________________________________________________________________________
Take it easy. I'm sure you will get on well with them.
                                                                                                                         Yours,
                                                                                                                         Li Ping
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