已知函数，则的值为(     )

温家宝总理曾寄语广大青年学生。他说，一个民族有一些关注天空的人，这个民族才有希望。他希望同学们经常仰望天空，学会做人，学会思考，学会知识和技能，做一个关心世界和国家命运的人。下面对“学会做人”与“学会知识和技能”的关系，表述正确的是 (　　)
①良好的科学文化修养能够促进思想道德修养
②加强思想道德修养能够促进科学文化修养
③科学文化修养水平提高了，思想道德修养水平自然而然就会提高
④思想道德修养比科学文化修养更重要

有NaCl、KSCN、NaOH、AgNO₃四种溶液，只用一种试剂就把它们鉴别开来，这种试剂是（   ）

我国改革开放新时期治国安邦的总章程是（    ）

根据对话内容，从方框内的选项中选出能填入空白处的最佳选项，选项中有两项为多余选项。
Mrs. Lee: Hello. 68178502.
David:  Hello.____  ?
Mrs. Lee: Sorry.____ . Can I take a message?
David:  Yes. This is David, Bruce’s friend. I want to ask him for some Chinese ancient coins. He told me he had got some recently. ____  . I don’t care if they were made of different metals. I just want to add some more coins in my collection.
Mrs. Lee: OK. I’ll tell him. Would you like him to ring you back later?
David:  Well, I won’t be at home later this day. Would you please ask him to ring me tomorrow morning?
Mrs. Lee: Sure.____ ?
David:   Oh, sorry.____   The new number is 66129853.
Mrs. Lee: OK. I’ll write a message for him.
David:   It’s really nice of you, Madam. Thank you very much. Goodbye!
Mrs. Lee:  Bye!

A. He’s not in at the moment. B. Who are you? C. My telephone number has changed. D. I’m not sure he would give me one or two. E. Could I speak to Bruce, please? F.I am very happy to hear that. G. Has he got your telephone number?