一个封闭透明的正四面体容器内装有水，正四面体的一个面放置在水_爱下问搜题

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问题单项选择题

一个封闭透明的正四面体容器内装有水，正四面体的一个面放置在水平桌面时，体内水面高度为四面体高h的，现将它倒置使原底面平行于水平桌面，此时水面的高度与h的比值为（）。

A.A

B.B

C.C

D.D

答案

参考答案：D

解析：

设正四面体的体积为V，正四面体倒置时水面的高度为h’。因为四面体体积之比等于高度之比的三次方，所以正四面体中水的体积为，由此可得，。故正确答案为D。

单项选择题

甘遂半夏汤出自

A．《内经》
B．《金匮要略》
C．《医门法律》
D．《儒门事亲》
E．《医宗金鉴

完形填空

Sports are by nature competitive. But recently, the over-competitive nature youth sports seem to have taken on has led to cause for ____.
Those who are strongly against competition point out that in a competition, only one wins while the rest ____. They argue that competition leads children to define themselves by the outcome, tying their self-esteem(自尊心) up with their ability to ____ others. They further argue that competition causes anxiety, affects learning and causes children to view others as____ to their success. Competition restricts participation and ___ success. A “win-at-all-costs” mentality can cause children to pay little attention to honesty and fair play.
On the opposite side of the debate are those who view competition as a ____ part of American society. They argue that placing kids in a competitive situation such as sports helps prepare them for a(n) ____ life in our society that is full of competition. ____ is a normal part of human nature and part of everyday life. Other arguments ____ competitive sports are that they provide challenges, help kids develop skills, and teach them how to get along with others.
The third side of this debate says that a little competition can’t be that ____, as long as competition does not get out of hand and take on a “win-at-all-costs” mentality. They claim that competition in itself is not bad and it can serve as a ____ of social comparison, necessary for adolescents to see how ____ they are. Their advice is to introduce competition ____ while focusing more on mastery and cooperation during childhood. The gradual shift toward competition will allow children to build skills, participate fully, and focus on ____ rather than winning.
It is important that you consider all of the possible ____ of competition before you put your child in a competitive situation.

D．invitations

A．Disagreement

D．Competition

C．interesting

C．responsibilities