问题 单项选择题

下列关于DNA结构与功能的说法,不正确的是()

A.DNA分子中G与C碱基对含量越高,其结构稳定性相对越大

B.碱基排列顺序的千变万化,构成了DNA分子的多样性

C.生物体所有DNA分子的转录和翻译是同时同地进行的

D.DNA分子结构相对稳定的重要原因之一是碱基互补配对原则保证了DNA复制的准确进行

答案

参考答案:C

阅读理解

In the United States, friendships can be close, constant, intense, generous, and real, yet fade away in a short time if circumstances (环境) change. Neither side feels hurt by this. Both may exchange Christmas greeting for a year or two, perhaps a few letters for a while --- then no more. If the same two people meet again by chance, even years later, they pick up the friendship where it left off and are delighted.

In the States, you can feel free to visit people’s homes, share their holidays, enjoy their children and their lives without fear that you are taking on a lasting obligation. Do not hesitate to accept hospitality because you cannot give it in return. No one will expect you to do so for they know you are far from home. Americans will enjoy welcoming you and be pleased if you accept their hospitality easily.

Once you arrive there, the welcome will be full and warm and real. Most visitors find themselves readily invited into many homes there. In some countries it is considered inhospitable to entertain at home, offering what is felt as “merely” home cooked food, not “doing something” for your guest. It is felt that restaurant entertaining shows more respect and welcome. Or for various other reasons, such as crowded space, language difficulties, or family custom, outsiders are not invited into homes.

In the United States, both methods are used, but it is often considered more friendly to invite a person to one’s home than to go to a public place, except in purely business relationships. So, if your host or hostess brings you home, do not feel that you are being shown inferior (差的) treatment.

Don’t feel neglected (被忽视) if you do not find flowers awaiting you in your hotel room either. Flowers are very expensive there, hotel delivery (递送,投递) is uncertain, arrival times are delayed, changed, or canceled – so flowers are not customarily (通常) sent as a welcoming touch. Please do not feel unwanted! Outward signs vary in different lands; the inward welcome is what matters, and this will be real.

小题1:In the United States, you will find friendships __________ if circumstances change.

A.die suddenly

B.pass away

C.disappear gradually

D.last forever小题2:Americans _________ their foreign friends to make a return for their hospitality.

A.ask

B.wish

C.never allow

D.don’t expect小题3:In some other countries, giving a dinner party at home is considered _______ than in a restaurant.

A.less formal

B.less hospitable

C.more natural

D.more popular小题4:According to the passage, which of the following is NOT true?

A.Flowers are available at all time.

B.Flowers are expensive.

C.Flowers are signs of outward welcome.

D.Flowers are not necessarily sent to guests.小题5:Which of the following is the best title for this passage?

A.American Hospitality

B.American Friendships

C.American Invitation

D.American Welcome

判断题