曲线y=x3﹣3x2有一条切线与直线3x+y=0平行,则此切线方程为[ ] A. 发布时间:2017-05-12 07:39 │ 来源:www.tikuol.com 题型:选择题 问题: 曲线y=x3﹣3x2有一条切线与直线3x+y=0平行,则此切线方程为[ ]A.x﹣3y+1=0B.3x+y+5=0C.3x﹣y﹣1=0D.3x+y﹣1=0
题型:选择题 完形填空。 We have known for a long time that flowers of different plants open and close at different times of day.This is so __1__ that there seems to be no need to ask the reason for it. Yet no one __2__ understands why flowers open and close like this at particular times. The process is not as __3__ as we might think,as recent experiments have shown. In one study, flowers were kept in constant __4__. We might expect that the flowers, without any information about the time of day, did not open as they __5_ do. As a matter of fact, they __6__ to open at their usual time. This suggests that they have some mysterious(神秘的) way of knowing the __7__. Their sense of time does not __8__information from the outside world; it is, so to speak, inside them, a kind of "inner clock". This __9__ may not seem to be very important. However, it was later found that not just plants but also __10__ , including man, have this "inner clock" which __11__ the working of their bodies and influences their activities. Men, then, are also influenced by this mysterious __12__. Whether we wish it or not, it affects such things in our life as our need for sleep, our need for food. In the past, this did not really __13__ because people lived in natural condition. In the __14__ world, things are different; now there are spacemen, airplane pilots and, in ordinary life, a lot of people who have to work at night. It would be very __15_ , then, to know more about the "inner clock". Such things as flowers might help us understand more about ourselves.( )1. A. familiar ( )2. A. partly ( )3. A. complex ( )4. A. quietness ( )5. A. finally ( )6. A. refused ( )7. A. time ( )8. A. deal with ( )9. A. discovery ( )10.A. beasts ( )11.A. controls ( )12.A. world ( )13.A. happen ( )14.A. ancient ( )15.A. hard B. strange B. personally B. simple B. darkness B. completely B. decided B. secret B. add to B. activity B. animals B. studies B. flower B. exist B. modern B. expensive C. similar C. really C. mature C. loneliness C. physically C. continued C. process C. give away C. invention C. strangers C. measures C. power C. matterC. wonderful C. convenientD. special D. willingly D. meaningful D. sadness D. normally D. failed D. study D. depend on D. method D. humans D. destroys D. experiment D. work D. peaceful D. important 查看答案
题型:选择题 文化认同作为小到一个群体、大到一个民族向心力的有机“粘合剂”,是凝聚这个群体和民族伟大精神力量的______。文化认同如果缺失,社会语境便趋于焦虑,人们的价值取向便会______,因为文化认同相对于政治认同和社会认同,具有更深远的______。依次填入划横线部分最恰当的一项是:A.基础 丧失 意义B.根本 丢失 价值C.根基 迷失 内涵D.基础 失落 涵义 查看答案