题目

已知曲线y=x2-4px＋1与x轴无公共点,Sn是数列{3·pn-1}的前n项和,则Sn为(    )A.           B.            C.3               D.1 答案：B分析：∵曲线y=x2-4px＋1与x轴无公共点,∴方程x2-4px＋1=0无实根.∴Δ=16p2-4＜0.∴|p|＜.∴数列{3·pn-1}是一个公比为p(|p|＜)，首项为3的无穷递缩等比数列.∴Sn=.Have you ever had a dream to make your home a happier place? Maybe there are some 　21 you can follow.Sometimes you don’t think your parents are fair to you. When you want to dress 　22 a modern way, your mum doesn’t 　23 you to wear a mini-skirt. When you are making phone calls to friends, they ask 　24 you are speaking to a boy or a girl. Sometimes it seems that you’re not as close to your parents as you used to be. How can you 　25 close again?Closing the gap by American writer Jay McGraw gives advice on how to have a better relationship with your 　26 . He gives ways to help you 　27 your parents. When you think, “my parents don’t want me to have any fun,” that usually means your parents want you to be 　28 . Both parents and children have 　29 . They need to feel they are important and loved. You should 　30 your parents your needs, and find out what their needs are. Then, you can think of a way to make all of you 　31 . He gives you some ideas:Make time to 　32 . You could talk about your school life and your plans for the future. 　33 a diary. This is to help you understand more about yourself and your feelings. Show your parents you are growing up. Wash your 　34 and help clean the house. Your parents will feel that you are no longer a little child. If you follow these, you will be able to break down 　35 between your parents and yourself.21. A. way　　　　 　　　　 B. advices　　　 　　　 C. suggestion　　　 　 D. points22. A. with　　　　 　 　　B. in　　　　　　　　　　　　　　 C. of　　　　　　 　 D. by23. A. hate　　　 　　 　　B. mind　　　　 　　　 C. like　　　　　　　　　　　　 D. dislike24. A. whether　　 　 　　B. what　　　　 　　　 C. why　　　　　 　 D. how25. A. go　　　　 　 　　B. look　　　　　　　　　　　　 C. become　　　　 　 D. is26. A. friends　 　　　 　　B. teachers　　　 　　 C. children　　　　　　　　　 D. parents27. A. listen to　　 　　 　　B. understand　　 　　 C. listen　　　　 　　 D. obey28. A. safe　　　　 　 　　B. dangerous　　 　　 C. angry　　　　 　　 D. sad29. A. need　　　　　　　　　 　 B. needs　　　　 　　 C. needed　　　　 　　 D. loved30. A. speak　　　 　　　 B. say　　　　　 　　 C. tell　　　　　 　　 D. told 31. A. nervous　　 　　 　　B. joyless　　　　 　　 C. excited　　　 　　　 D. happy32. A. talk　　　　　　　　　　 　 B. tell　　　　　 　　 C. smile　　　　 　　 D. learn33. A. Write　　　 　 　　B. Have　　　　 　　　 C. Keep　　　　 　　 D. Read34. A. hands　　 　　 　　B. face　　　　　 　　 C. socks　　 　　　　 D. clothes35. A. the ways　 　　 　　B. the walls　　 　　　 C. the needs　　 　　　 　　D. the plans