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问题 填空题
(1-
x
)20的二项展开式中，x的系数与x9的系数之差为______．
答案

展开式的通项为Tr+1=(-1)r

Cr20
x
r
2

令

r
2
=1得r=2；令
r
2
=9得r=18

∴x的系数与x9的系数C202，C2018

∴x的系数与x9的系数之差为C202-C2018=0

故答案为：0

单项选择题

重症肌无力危象抢救的关键是（）。

A.积极控制感染

B.肌内注射新斯的明

C.给予免疫抑制剂

D.辅助通气

E.去除使病情加重的诱因
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单项选择题

A narrowing of your work interests is implied in almost any transition from a study environment to managerial or professional work. In the humanities and social sciences you will at best reuse only a fraction of the material (1) in three or four years’ study. In most career paths academic knowledge only (2) a background to much more applied decision-making. Even with a " training " form of degree, (3) a few of the procedures or methods (4) in your studies are likely to be continuously relevant in your work. Partly this (5) the greater specialization of most work tasks compared (6) studying. Many graduates are not (7) with the variety involved in (8) from degree study in at least four or five subjects a year to very standardized job (9) . Academic work values (10) inventiveness, originality, and the cultivation of self-realization and self-development. Emphasis is placed (11) generating new ideas and knowledge, assembling (12) information to make a " rational " decision, appreciating basic (13) and theories, and getting involved in fundamental controversies and debates. The humanistic values of higher (14) encourages the feeling of being (15) in a process with a self-developmental rhythm. (16) , even if your employers pursue enlightened personnel development (17) and invest heavily in " human capital " —for example, by rotating graduate trainees to (18) their work experiences—you are still likely to notice and feel (19) about some major restrictions of your (20) and activities compared with a study environment.

5（）

A.reflects

B.affects

C.checks

D.reduces
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