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问题 单项选择题

《建设工程委托监理合同(示范文本)》规定，实施监理工作过程中的额外工作是指 ( )。

A．承包人的原因施工不能按期竣工，监理人延长监理工作时间
B．委托人原因导致施工合同终止，致使监理业务终止后的善后服务
C．委托人要求增加监理工作范围，而增加的监理工作量
D．承包人的原因，使监理工作受阻，导致增加的监理工作量

答案

参考答案：B

选择题

下列说法中，正确的是（  ）

A．电场强度和电势都是矢量

B．同一等势面上的各点电势相等，电场强度也相等

C．在同一等势面上移动电荷，电场力一定不做功

D．电场中的两条电场线一定不会相交，但两个电势不等的等势面有可能相交
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单项选择题

The sun today is a yellow dwarf star. It is fueled by thermonuclear reactions near its center that convert hydrogen to helium. The sun has existed in its present state for about 4 billion, 600 million years and is thousands of times larger than the Earth.
By studying other stars, astronomers can predict what the rest of the sun’s life will be like. About 5 billion years from now, the core of the sun will shrink and become hotter. The surface temperature will fail. The higher temperature of the center will increase the rate of thermonuclear reactions. The outer regions of the sun will expand approximately 35 million miles, about the distance to mercury, which is the closest planet to the sun. The sun will then be a red giant star. Temperatures on the earth will become too hot for life to exist.
Once the sun has used up its thermonuclear energy as a red giant, it will begin to shrink. After it shrinks to the size of the earth, it will become a white dwarf star. The sun may throw off huge amounts of gases in violent eruptions called nova explosions as it changes from a red giant to a white dwarf.
After billions of years as a white dwarf, the Sun will have used up all its fuel and will have lost its heat. Such a star is called a black dwarf. After the Sun has become a black dwarf, the earth will be dark and cold. If any atmosphere remains there, it will have frozen onto the earth’s surface.

When the sun becomes a red giant, what will conditions be like on Earth

A．Its atmosphere will freeze and become solid.
B．It will be enveloped in the expanding surface of the sun.
C．It will become too hot for life to exist.
D．It will be nearly destroyed by nova explosions.
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