题目

22．已知某DNA分子片段所转录的信使RNA中腺嘌呤占17%，尿嘧啶占21%，则这个DNA片段中胸腺嘧啶占（   ） A．17%        B．19%        C．21%        D．38% 答案：B听下面5段对话。每段对话后有一个小题，从题中所给的A、B、C三个选项中选出最佳选项，并标在试卷的相应位置。听完每段对话后，你都有10秒钟的时间来回答有关小题和阅读下一小题。每段对话只读一遍。1. How much was the TV set?A. $60.B. $120.C. $90.2. Where will the two speakers meet this evening?A. At Peter's place.B. At Tom's house.C. At the woman's flat.3. Where was Peter after he finished his school?A. In England.B. In Australia.C. In America.4. What will the two speakers do?A. Visit the new school.B. Go to the new restaurant.C. Sell some pudding.5. What can be concluded about Judy?A. Judy came to the party.B. Judy planned the party.C. Judy hasn't appeared yet.