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问题 填空题
若x+1＞0，则x+
1
x+1
的最小值为______．
答案

因为x+1＞0，所以x+

1
x+1
=x+1+
1
x+1
-1≥2
(x+1)•
1
x+1
-1=1．

当且仅当x+1=

1
x+1
，即x=0时“=”成立．

所以x+

1
x+1
的最小值为1．

故答案为1．

单项选择题

该患儿发作的机理是

A．脱水、血液黏稠

B．脑血栓形成

C．肺动脉漏斗部痉挛

D．感染侵犯脑实质

E．心功能不全
查看答案
单项选择题

In June of 1973, nine whales beached on the Florida coast. Beaching means swimming out of the ocean onto the beach, and usually dying there. No one knows why they do it, but a number of whales beach themselves every year. Some people think beaching is an accident.
Perhaps the whales get confused. Scientists who studied the beaching of three dozen whales in Australia think the whales may have been confused by loud noises, Whales can tell where they are by sounds. They send out sounds and listen as they travel past or bounce off objects. Two days before these thirty-six whales beached, loud guns had been fired for two hours. The loud sounds may have confused the whales. Their confusion might have caused them to wander into low water.
Whatever the reason whales beach, it is a sad event. People try to save them, but very few beached whales live. One whale that was rescued from beaching in Florida lived for forty-five days. That is the longest a beached whale has ever survived. And it lived that long only because it got attention from doctors.
All over the world, scientists rush to whale beachings as soon as they hear about them. They hope to learn why whales beach, and how to save them.

One reason whales beach may be ______.

A．because they are hungry

B．because they are attacked

C．that people can study them

D．that they are confused
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