下列化合物反应在 2%AgNO3-乙醇溶液中反应活性最高的是( ):(A)1-溴丁烷 (B)1-氯丁烷 (C)1-碘丁烷
A. 1-溴丁烷
B. 1-氯丁烷
C. 1-碘丁烷
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下列化合物反应在 NaI-丙酮溶液中反应活性最高的是( )
A. 3-溴丙烯
B. 溴乙烯
C. 1-溴乙烷
D. 2-溴丁烷
顺-和反 -1-叔丁基 -4-氯环己烷分别与热的氢氧化钠乙醇溶液反应(E2 机理 ),哪一个较快?( )
A. 顺-
B. 反 -
[音频]PartIListeningComprehension(20minutes)SectionADirections:Inthissectionyouwillhear10shortconversations.Attheendofeachconversation,aquestionwillbeaskedaboutwhatwassaid.Boththeconversationandthequestionwillbespokenonlyonce.Aftereachquestiontherewillbeapause.Duringthepause,youmustreadthefoursuggestedanswersmarkedA),B),C)andD)anddecidewhichisthebestanswer.1.A) Their parents cut back the loan.B) The woman doesn't want Frank to take another English courseC) They can't pay the rent this month.D) The woman's boss refused to give her a raise.2.A) Ask Dr. Smith to alter his decision.B) Ask Dr. Smith to call the library.C) Get the book directly from Dr. Smith.D) Get Dr. Smith's written permission.3.A) $120B) $108C) $90D) $404.A) He feels unsympathetic.B) He feels it's a pity.C) He feels it's unfair.D) He feels glad.5.A) Doing business.B) Taking pictures.C) Buying cameras.D) Making movies.6.A) Looking for an apartment.B) Looking for a job.C) Taking a suburban excursion.D) Asking the man for his opinions.7.A) She'll go to her uncle's.B) She has an appointment with her friend.C) She'll have an appointment with her friend.D) She'll have a visitor.8.A) He made a sudden turn.B) He drove the bus over a bicycle.C) He tried to avoid hitting the truck.D) He was driving too fast.9.A) He is curious.B) He is impatient.C) He is exhausted.D) He is satisfied.10.A) She didn't know how to use the new oven.B) She wanted her refrigerator to be fixed.C) There is something wrong with the oven.D) There is something wrong with the food.
下列属于心血管系统药物特点的是( )
A. 种类繁多且更替快
B. 作用机制复杂
C. 作用靶点多
D. 新型作用机制药物不断出现