题目内容

下列化合物中，同时有σ→σ、n→σ、n→π、π→π跃迁的化合物是()。

A. 一氯甲烷
B. 乙醛
C. 1，3-丁二烯
D. 苯酚

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A．It doesn't have a nice view.B．It doesn't come with a sauna bath.C．It's too expensive

A. It doesn't have a nice view.
B. It doesn't come with a sauna bath.
C. It's too expensive.
D. It doesn't have a kitchenette.

用NaOH溶液滴定某弱酸HA时(两者浓度相同)，当滴定至一半时，溶液的pH值为5．00；当滴定至化学计量点时，溶液的pH值为8．00；当滴定至200％时溶液pH值为12．00。则该酸(HA)的pKa值是()。

A. 5．00
B. 8．00
C. 12．00
D. 7．00

听力原文：W: Hello. Holiday Hotel. May I help you？
M: Yes, I'd like to reserve a room for a couple on the 13th of September.
W: Okay. Let me check our books here for a moment. You want a room for a couple on the 13th of October, right？
M: No. It is September, not October.
W: OH, I'm sorry. Let me see here. Hmm.
M: Are you all booked that night？
W: Well, not yet. We do have one suite available, complete with a kitchenette and a sauna bath. And the view of the sea is great, too.
M: How much is that？
W: It's only $ 200 dollars, plus a 10% room tax.
M: Oh, I'm afraid that's a little too expensive for me. Do you have a cheaper room available either on the 12th or 14th？
W: Well, would you like a smoking or a non-smoking room？
M: The non-smoking one, please.
W: Okay, we do have a few rooms available on the 12th; we're full on the 14th, unless you want a smoking room.
M: Well, how much is the non-smoking room on the 12th？
W: 80 dollars, plus the 10% room tax.
M: Okay, that'll be fine. I'll take this one.
W: An right. Could I have your name, please？
M: Yes. Torn Delfino.
W: How do you spell your last name, Mr. Delfino？
M: D-E-L-F-I-N-O.
W: Okay, Mr. Delfino, we look forward to seeing you on September 12th.
M: Okay. Goodbye.
(23)

A non-smoking room.
B. A smoking room.
C. A suite with a kitchen.
D. A room with a great view.

气液色谱可以通过()改变柱子的选择性。

A. 改变载气的种类和流速
B. 改变载体的种类和粒度
C. 改变固定相的种类和柱温
D. 改变固定相的涂渍量