题干

若sin(π﹣α)=2cosα,则 (x+α
t
a
n
x
)
6 展开式中常数项为(   )

A:52

B:160

C:−52

D:﹣160

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答案(点此获取答案解析)

B

同类题3

阅读下文,回答相关问题。

                                                                                                            不畏困难
        人们的脚步走向成功时,往往会遇到一些困难。有的人战胜了困难,最终成为事业的成功者;而有的人却畏惧困难,对事业冷冷淡淡、毫无信心,最终成为一个精神堕落的流浪汉。所以我认为,不管在什么情况下,遇到什么困难,都不应该畏惧。
        被誉为“当代神农氏”的科学家袁隆平,他掀起的粮食生产业的“绿色革命”席卷了神州,震惊了世界。他从一个普通的农村教师到取得划时代的科学成就,历经了漫长的岁月,终于在这场艰难曲折高度复杂的科学实践中脱颖而出。如果他畏惧了困难,就不会取得这样大的成就,而且更不会被誉为“当代神农氏”的称号。
         还有,全身瘫痪的张海迪,由于手不能拿书,就利用平面镜成像的原理,将书放在桌上对着镜子看到字,经过艰苦的斗争终于成为一代楷模。这样大的困难,张海迪都能克服,我们还有什么理由畏惧困难。
         以上事实足以证明,困难是没有什么可怕的,只要努力克服,困难一定会被我们打败的,而且我们会真正体会到生活的乐趣。既然如此,我们何不努力同困难斗争一番呢?

同类题5

阅读理解

    A 17-year-old boy, caught sending text messages in class, was recently sent to the vice principal's office at Millwood High School in Halifax, Nova Scotia. The vice principal, Steve Gallagher, told the boy he needed to focus on the teacher, not his cellphone. The boy listened politely and nodded, and that's when Mr. Gallagher noticed the student's fingers moving on his lap. He was texting while being scolded for texting. “It was a subconscious act,” says Mr. Gallagher, who took the phone away. “Young people today are connected socially from the moment they open their eyes in the morning until they close their eyes at night. It's compulsive.”

    A study this year by psychology students at Covenant College in Lookout Mountain, Ga., found that the more time young people spend on Facebook, the more likely they are to have lower grades and weaker study habits. Heavy Facebook users show signs of being more sociable, but they are also more likely to be anxious, hostile or depressed. (Doctors, meanwhile, are now blaming addictions to 'night texting' for disturbing the sleep patterns of teens.)

    Almost a quarter of today's teens check Facebook more than 10 times a day, according to a 2009 survey by Common Sense Media, a nonprofit group that monitors media's impact on families. Will these young people get rid of this habit once they enter the work force, or will employers come to see texting and 'social-network checking' as accepted parts of the workday?

    Think back. When today's older workers were in their 20s, they might have taken a break on the job to call friends and make after-work plans. In those earlier eras, companies discouraged non-business-related calls, and someone who made personal calls all day risked being fired. It was impossible to imagine the constant back-and-forth texting that defines interactions among young people today.

    Educators are also being asked by parents, students and educational strategists to reconsider their rules. “In past generations, students got in trouble for passing notes in class. Now students are skilled at texting with their phones still in their pockets,” says 40-year-old Mr. Gallagher, the vice principal, “and they're able to communicate with someone one floor down and three rows over. Students are just fundamentally different today. They will take suspensions rather than give up their phones.”