alist=[3,4,5,7,9,12,13,15,17] blist=alist[3:7:2] print（blist)运行结果是：

No one doubts the power of the media, and no one doubts the media is useful to those in power. Newspapers have vast【B1】______compared with any other published print, they are published frequently, and are【B2】______through wide distribution networks. For most people, they【B3】______the most substantial consumption of printed discourse(语段). 【B4】______the powerful in society should attempt to control and influence them is【B5】______question. 【B6】______there is also a conflicting myth of the freedom of the press, that journalists are free to give an objective【B7】______of anything they think newsworthy. And that, 【B8】______journalists on a particular newspaper may be constrained(限制)about what they can report, the reader has a choice because of the variety of newspapers on【B9】______. Newspapers in this regard have been【B10】______as the third estate, an essential ingredient of democracy; the information they give is【B11】______to be sufficiently important and trustworthy to allow voters to make judgments about the record of the political parties【B12】______elections and to make informed decisions about which party to【B13】______. Lord Northcliffe, the newspaper owner, once said that the real news is something that【B14】______wants to hide, and that all the rest is advertising. He obviously saw the【B15】______of the press as a watchdog for any inefficiency, irrationality, injustice, corruption of scandalous(丑恶可耻的)behavior. for which those in power may have been【B16】______However the press as we know it has been hijacked by those with political and economic power. First, they have done this through ownership. Second, they have done so by the dependence of newspapers on advertising. Third , they have【B17】______the ambiguities in what is news-worthy to their own【B18】______And lastly they dominate the way the world is represented in the news since they arc gatekeepers controlling the【B19】______of the news and are being【B20】______quoted in it.

1[A]?circuits????[B]?circulations????[C]?dispatches????[D]?cycles

2[A]?accessible????[B]?affordable????[C]?abundant????[D]?approachable

3[A]?consist????[B]?institute????[C]?construct????[D]?constitute?

4[A]?What????[B]?How????[C]?That????[D]?Why?

5[A]?in????[B]?beyond????[C]?without????[D]?beside?

6[A]?Thus????[B]?Meanwhile????[C]?Although????[D]?However?

7[A]?account????[B]?editorial????[C]?statement????[D]?comment???????

8[A]?only?if????[B]?if?only????[C]?as?long?as????[D]?even?if?????

9[A]?display????[B]?offer????[C]?exhibit????[D]?show??

10[A]?put?aside????[B]?taken?over????[C]?looked?down?upon??[D]?held?up???????

11[A]?counted????[B]?speculated????[C]?supposed????[D]?estimated????

12[A]?contesting????[B]?competing????[C]?contending????[D]?hosting?

13[A]?go?in?for????[B]?fall?back?on????[C]?make?for????[D]?vote?for?

14[A]?anyone????[B]?someone????[C]?everyone????[D]?nobody?

15[A]?post????[B]?feature????[C]?vehicle????[D]?role?

16[A]?responsible????[B]?conscientious????[C]?attributable????[D]?guilty???

17[A]?explored????[B]?probed????[C]?clarified????[D]?exploited???

18[A]?destinations???[B]?ends????[C]?objects????[D]?initiatives?

19[A]?sources????[B]?resources????[C]?causes????[D]?facilities?

20[A]?instantly????[B]?presumably????[C]?ultimately????[D]?constantly?

A、[1, 2, 3, 1, 2, 3, 1, 2, 3]

B、[1, 1, 1, 2, 2, 2, 3, 3, 3]

C、[[1, 2, 3], [1, 2, 3], [1, 2, 3]]

D、其余选项都不对

A、[1, 2, 3, 1, 2, 3, 1, 2, 3]

B、[1, 1, 1, 2, 2, 2, 3, 3, 3]

C、[[1, 2, 3], [1, 2, 3], [1, 2, 3]]

D、[1, 2, 3]

设α₁=(1，0，2，3)^T，α₂=(1，1，3，5)^T，α₃=(1，-1，a+2，1)^T，α₄=(1，2，4，a+8)^T，β=(1，1，6+3，5)^T．

??(1) a，b为何值时，β不能表示为α₁，α₂，α₃，α₄的线性组合？

??(2) a，b为何值时，β可以由α₁，α₂，α₃，α₄的线性表出，且表示唯一？

，则|A^-1-2A*T|=_.

R³中，取两个基

??α₁=(1，2，-2)^T，α₂=(2，3，3)^T，α₃=(3，7，1)^T；

??β₁=(3，1，4)^T，β₂=(5，2，1)^T，β₃=(1，1，-6)^T，试求坐标变换公式．