题目

对于多细胞生物而言，下列有关细胞生命历程的说法，正确的是              (     )       A.细胞分化导致细胞中的遗传物质发生改变     B.细胞癌变是所有细胞都要经历的一个阶段 C.细胞衰老时细胞呼吸的速率减慢                        D.细胞死亡是细胞癌变的结果 答案：C 解析: 略　　On September 4th of 2004 my American friend Jon Hageseth took me to the airport in La Crosse, Wisconsin to fetch a new suitcase. To show my thanks, I treated him and his wife with a Mexican lunch on the way back. After we enjoyed the delicious food, I paid the bill and went towards the car, but just when everyone was seated, Jon's wife Cathy returned to the restaurant. I felt puzzled. Upon her return, she said,“You were clever not paying the tip, so I had to go back to pay it.”I felt so embarrassed that I lost no time to apologize, explaining that there is no such a practice in China. In fact, I don't take the tipping issue seriously although I am aware of such a practice in the US. 　　Another day in September, I dined with one of my American colleagues at a Buffet Restau rant. On finishing the meal I began searching my wallet for small notes.“What are you doing, Zhao Qi?”my colleague asked.“To pay the tip of course.”My colleague burst into laughter,“You don't have to.” “Why?”I asked and recalled my previous embarrassing experience in the Mexican restaurant. And then she told me that it's unnecessary to pay tips at any kind of self-service restaurants, but we have to pay tips only in restaurants where services are provided. I still did not get a clear picture of this issue. Seeing my puzzlement, she offered me some good advice on the situation I should give the tip. 　　In her opinion, tipping plays an important role in US economy and acts as an unavoidable part of American's daily life. The following are a few facts about tipping taken from various university and market-research studies. 　　1．People eating at restaurants in the US pay about $16 billion a year in tips. 　　2．Waiters and waitresses who wait on tables receive much higher tips than those who don't. 　　3．Waitresses who add a“smile”face to their hills see their tips increase about 5％. Men who do the same watch theirs drop 3％. 　　4．94％of Americans regularly tip when eating out. 　　According to my own experience and those various studies, I may conclude that tipping reflects a kind of good manners and appreciation, not as simple as we imagine. (1) The underlined word“embarrassed”probably has the same meaning as ________. [　　] A．ashamedB．thankful C．unsatisfiedD．shocked (2) What difficulty did the writer have in giving tips in America? [　　] A．Not making sure how much should be given. B．Not knowing what occasion she should tip. C．There isn't such a practice in China. D．Not willing to offer tips. (3)From the studies we can know that ________. [　　] A．every American tips when having meals out B．only a small amount of money is spent on tips in America C．a smile on a waitress' face can increase the tip D．smiles benefit both waiters and waitresses