下列关于两个图形位似的叙述不正确的是( )A.每对对应点所在的直线相交于同一点

题型:选择题

问题:

下列关于两个图形位似的叙述不正确的是(   )

A.每对对应点所在的直线相交于同一点
B.两个图形上的对应线段之比等于位似比
C.两个图形上的对应线段必平行
D.两个图形的面积比等于位似比的平方
考点:位似
题型:选择题

What’s the red star in the sky through a telescope(望远镜)? It is Mars. Do you want to know more about it? Take the “Mars Orbit Express”!

“Mars Orbit Express” is a space probe (探测器). It was sent towards Mars by American scientists on August 12th,2005. Its tasks are to study Mars’ atmosphere and return photos to Earth. But before that “Mars Orbit Express” must travel about 100 hundred million kilometers and seven months. It reached Mars’ orbit(轨道)in March,2006.

Mars and Earth have similar weight and size. However,Mars is closer to the sun than Earth. Mars is very cold. The average temperature is below 50℃. The temperature at noon only reaches 20℃ during a Mars day. Its atmosphere is mostly CO2. It has much sand and two moons---Phobos and Deimos.

Scientists think Earth and Mars had similar beginnings 4.6 billion years ago. But while Earth supports millions of lives,Mars becomes bad. “Earth easily could have turned out like that.” said an scientist, “It is important for us to find out why and Mars Orbit Express’ should do that.” “Mars Orbit Express” also would help scientists to learn what might happen to Earth in the future.  “Mars Orbit Express” would work for about four years.

小题1: What can you see through a telescope when watching Mars? ________.

A.Much sand

B.A red star

C.Its atmosphere

D.Its size小题2:One of the tasks of Mars Orbit Express is _______.

A.taking pictures of Mars

B.studying the weight of Mars

C.finding out distance between Earth and Mars

D.telling the time it takes to go from Earth to Mars小题3:Compared with Earth,_______.

A.Mars has a long history

B.Mars is big and heavy

C.Mars is close to the sun

D.Mars’ atmosphere is mainly O2.小题4: Which might be the proper title for the passage?

A.Mars:differences from Earth

B.A probe:to learn more about Mars

C.Mars: change of temperature

D.A probe:to tell the future of Earth

题型:选择题

焊后热处理中,回火处理的目的有()。

A.调整工件的强度、硬度及韧性

B.细化组织、改善切削加工性能

C.避免变形、开裂

D.保持使用过程中的尺寸稳定

题型:选择题

气源处理元件中的分水滤气器()打开下端的放水阀一次,()取下过滤杯与有水杯清洗一次。

A、每天、每两周

B、每周、每两月

C、每月、每半年

题型:选择题


A.不能忽视名利

B.不该只看眼前

C.不该看重名利

D.不该轻视名利

题型:选择题

操作系统是用户和计算机之间的桥梁,它的两大主要任务是( )。

A.对数据库的会计数据进行处理

B.向用户提供一个清晰、简单、易用的友好界面

C.管理计算机的硬件资源

D.管理计算机的硬件资源的软件资源

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