用来体现经济变量与时间的变化关系的经济数学的内容为( )。A．几何代数 B．线性代

阅读理解。

     The oldest stone buildings in the world are the pyramids. They have stood for nearly 5000 years, and it

seems likely that they will continue to stand for thousands of years yet. The most famous of these are the

"Step" pyramid and the "Bent" pyramid.

     Some of the pyramids still look much as they must have done when they were built thousands of years

ago. Most of the damage (破坏) has been at the hands of men who were looking for treasure or, more often,

for stones to use in modern buildings. The dry climate of Egypt has helped to preserve the pyramids, and their

very shape has made them less likely to fall into ruin (废墟). These are good reasons why they can still be

seen today, but perhaps the most important is that they were planned to last forever.

     It is most likely that plans were made for the building of the pyramids because the plans of other large

works have fortunately been preserved. But, there are no writings or pictures to show us how the Egyptians

planned or built the pyramid themselves. As a result, we are only able to guess at the methods used.

However, one thing is certain: there must have been months of careful planning before they could begin to

build. The first thing they had to do was to choose a suitable place. You may think this would have been easy

with miles and miles of empty desert around, but a pyramid could not be built just anywhere. Certain rules

had to be followed, and certain problems had to be overcome.

     The pyramid had to be on the west side of the Nile, the side on which the sun sets. This was for religious

reasons. The pyramid also had to stand well above tho level of the river to protect it against the regular floods.

The pyramid could not be too far from the Nile, however, as the stones to build it needed to be carried in boats

down the river to the nearest point. Water transport was, of course, much easier than land transport. The

builders also had to find a rock base which was not likely to crack under the great weight of the pyramid.

Finally, the pyramid had to be near the capital, or better still, near the king's palace so that he could visit it

easily and personally check the progress being made on the final resting place for his body.

1. Most of the damage to the pyramids has been caused by _______.

A. stones

B. rivers

C. weather

D. men

2. What's the meaning of the underlined word preserve?

A. Damage.

B. Protect.

C. Build.

D. Cover.

3. What was the first thing people had to do before they could begin to build?

A. To follow the rules.

B. To draw the pictures.

C. To choose the right place.

D. To find the workers.

4. To protect a pyramid from floods they could have built it a long way from the Nile, but _______.

A. it had to be built on the west side of the river Nile where the sun sets

B. it was difficult to find a large enough rock base so far from the fiver

C. this would have been impossible because of religious reasons

D. this would have made it very difficult to transport the materials

在竖直平面内存在着某一匀强电场，一带电量为+q的小球以一定初速度v₀进入光滑的绝缘材料做的竖直放置的固定半圆管左端后，小球在管内一直做减速运动，最后从半圆管右出口飞出。整个运动过程不考虑空气阻力与摩擦阻力。以下判定正确的有

A．小球在半圆管内运动过程中克服电场力做功的一定大于mgR

B．小球在半圆管内运动过程中克服电场力做功的可能小于02mgR

C．小球的电势能一定先增加后减小

D．小球受到的电场可能与重力大小相等

某单位于2008年10月19日开出一张支票。下列有关支票日期的写法中符合要求的是( )。

A．贰零零捌年拾月拾玖日

B．贰零零捌年壹拾月壹拾玖日

C．贰零零捌年零壹拾月拾玖日

D．贰零零捌年零壹拾月壹拾玖日

只有使自身所处的区域环境和世界环境保持稳定，中国才能够持续地繁荣发展。因此，中国必须设法控制其发展和增长方式，打消其他国家的______，减少它们对中国崛起的担忧，并防止它们______甚至______中国。
依次填入画横线部分最恰当的一项是( )

A．疑虑 限制 遏制

B．顾虑 限制 控制

C．疑惑 遏制 控制

D．忧虑 遏制 限制

集中润滑系统采取递进式润滑。