从正方体的八个顶点中任取三个点为顶点作三角形，其中直角三角形_爱下问搜题

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问题填空题

从正方体的八个顶点中任取三个点为顶点作三角形，其中直角三角形的个数为_______。

答案

48

每个表面有个，共个；每个对角面有个，共个.

阅读理解

阅读理解。

Steve Jobs was one of the fathers of the personal computing time and the founder of Apple. He was also one of the giants of the information age. Here are some of his greatest contributions.

Apple II Jobs and Steve Wozniak founded Apple Computes Inc. in 1976. A year later, the Apple II was invented. This production (产品) was the world's first mass-market personal computer.	Apple II Jobs and Steve Wozniak founded Apple Computes Inc. in 1976. A year later, the Apple II was invented. This production (产品) was the world's first mass-market personal computer.
Apple II Jobs and Steve Wozniak founded Apple Computes Inc. in 1976. A year later, the Apple II was invented. This production (产品) was the world's first mass-market personal computer.	Apple II Jobs and Steve Wozniak founded Apple Computes Inc. in 1976. A year later, the Apple II was invented. This production (产品) was the world's first mass-market personal computer.

1. When did the iMac first come out?

A. In 1976.
B. In 1998.
C. In 2010.
D. In 2011.

2. Which one was the oldest?

A. The Apple II.
B. The iMac.
C. The iPad.
D. The Iphone 4s.

3. From the passage, we can know that the iPad ______.

A. has a better camera.
B. is the first personal computer.
C. has a CD-ROM slot.
D. is great for watching movies.

单项选择题

劳动力供给富有弹性表示为( )。

A．E_S＜0

B．E_S＞0

C．E_S＜1

D．E_S＞1