石膏硬化后体积有微小膨胀，故常用于制作石膏模型。

The question whether there is life on Mars (火星) has made the public think a lot for more than a century. The closest look showed Mars to be a dusty, cold world, covered by air too thin to breathe. A British spaceship and Europe's Mars spaceship plan to land on Mars or enter orbit (轨道) around it. One of the NASA’s (美国宇航局) spaceships is expected to land on January 3, the other is going to land on the opposite side of Mars on January 24. Since 1960, over twenty spaceships sent to Mars have failed. Most have been lost on flying up or landing because those are the most difficult times of any flights.     Scientists wanted to find out whether there was water in Mars. In October, a team of scientists reported that Mars had been a dry wasteland. But weeks later, a second team reported differently that they had found some marks showed clearly that they were made by the rivers. Such marks told us that Mars was a warmer place billions of years ago — just as life first appeared here on Earth. Scientists at once raise a question: if what they said is true, what happened on Mars? Then what about the earth?

小题1:Which is right about Mars?

A．It’s cold without dust.

B．There is no water or air.

C．It’s warm with some thin air.

D．It’s a dusty, cold world almost without air.小题2:Two NASA’s spaceships _______________.

A．will land on the different sides of Mars

B．will land on the same day

C．will enter orbit around Mars

D．will land with a man小题3:The most difficult times of a flight are _______________.

A．taking off

B．flying up and arriving

C．entering the orbit and landing

D．leaving the earth and entering the orbit小题4:A team of scientists reported that there might be_____________ in Mars.

A．nothing but air

B．nothing

C．water billions of years ago

D．thick air and lakes小题5:What are scientists worried about when they raise the question?

A．Life disappeared on Mars.

B．Spaceships can’t land on Mars.

C．The air on the earth gets less and less.

D．The earth might be changed like Mars

在岩土参数标准值计算中，常采用公式此式在统计学中采用的单侧置信概率为（）。

A.0.99

B.0.975

C.0.95

D.0.90

竖向结构(墙、柱等)浇筑混凝土前，底部应先填( )厚的与混凝土内砂浆成分相同的水泥砂浆。

A．10～30mm

B．30～50mm

C．50～100mm

D．50～70mm

根据乔姆斯基20世纪50年代建立的形式语言的理论体系，语言的文法被分为四种类型，即：O型(上下文有关文法)、1型(上下文相关文法)、2型(上下文无关文法)和3型(正规文法)。其中2型文法与 (66) 等价，所以有足够的能力描述多数现今程序设计的语言的句法结构。一个非确定的有限自动机必存在一个与之等价 (67) 。从文法描述语言的能力来说， (68) 最强， (69) 最弱，由四类文法的定义可知： (70) 必是2型文法。

（70）处填（）。

A．0型文法

B．1型文法

C．2型文法

D．3型文法

全口义齿选磨时，正中一侧上颌舌尖早期接触，侧方也有早期接触，则应选磨（）

A.上颌舌尖

B.下颌舌尖

C.上颌颊尖

D.下颌颊尖

E.下颌中央窝