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问题 选择题

设NA为阿伏加德罗常数，下列说法中正确的是[ ]

A．1mol Na2SO4溶于水中，所得溶液中Na+个数为NA

B．H2、O2、N2、CO2组成的混合气体1mol在标准状况下的体积约为22．4L

C．1L 0．3mol·L-1Na2SO4溶液中，含有Na+和SO42-总数为0．6NA

D．NA个氢气分子（H2）的质量为1g

答案

答案：B

补全对话，情景问答

根据对话语境和所给首字母提示，填写正确的单词完成对话

A: Good morning.I'd like to see Mr Brown.

B: Do you have an a  1   ?

A: No,I'm a  2   not.I've just arrived in the town today.

B: Mr Brown is quite busy.I'm afraid he won't be able to see you today.

A: Do you think I can see him t  3   ?

B: Let me see. He's f  4   at 2:30 tomorrow afternoon. Can you come here on t  5   ?

A: Yes,I'll be here at 2:30. Thank you.

B: You are w  6  . Goodbye.
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单项选择题

J2EE的四层体系架构(客户层/表示层/业务逻辑层/数据层)中，可用来实现表示层的技术是______。

A．Java Servlets

B．Enterprise JavaBeans

C．Internet Explore

D．Database
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