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问题 填空题
在(
x
-
1
2x
)10展开式中，含x的负整数指数幂的项共有 ______项．
答案

(

x
-
1
2x
)10展开式的通项为Tr+1=(-
1
2
)r
Cr10
x
10-3r
2
其中r=0，1，2…10

要使x的指数为负整数有r=4，6，8，10

故含x的负整数指数幂的项共有4项

故答案为：4

单项选择题

In June 1985, two British mountaineers Joe Simpson and Simon Yates made the first-ever climb of the 21,000-foot snow-covered Siula Grande mountain in Peru. It was an exceptionally (26) job, but nothing compared to what was to (27) . Early in the process, Simpson (28) and broke his right knee. Yates could have (29) him but managed to find a way of (30) him down the mountains on a rope in a series of difficult drops. Then Simpson fell into a crevasse and Yates eventually had no (31) but to cut the (32) , completely convinced that his friend was now (33)

In his book on the (34) , Joe Simpson wrote:

(35) I looked at the distant moraines, I know that I must at least try I would probably (36) there among those rocks. If I died, well, that wasn’t so (37) , but I wouldn’t have (38) waited for it to happen. The (39) of dying no longer affected me as it had in the crevasse at first. I now had a chance to (40) it and struggle against it.

The survival of Yates himself was (41) . That Simpson somehow found a way of (42) out of the crevasse after 12 hours and then crawled and (43) himself six miles back to camp, (44) three days and might without food or drink, would be considered as a heroic fiction. But in fact it was so (45) .

31().

A. idea

B. hope

C. choice

D. chance
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单项选择题

经纬仪的主要轴线是哪些（）

A.水准管轴、视准轴、定位轴线

B.水准管轴、竖轴、横轴、视准轴、定位轴线

C.水准管轴、竖轴、横轴、视准轴

D.水准管轴、竖轴、横轴、定位轴线
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