问题
单项选择题
在采气工艺中，（）安装时有方向性。
A.闸阀
B.平板阀
C.节流阀
D.旋塞阀
答案
参考答案：C
搜题请搜索小程序“爱下问搜题”
在采气工艺中，（）安装时有方向性。
A.闸阀
B.平板阀
C.节流阀
D.旋塞阀
参考答案：C
| 阅读理解。 | ||
| An Experiment Materials: Newspaper, "ACE" hardware ruler (1/8" thick), a flat table. Purposes: We'll show that there is air pressure pushing on us, from every direction while we're on this Earth. Procedure:
the edge of the table. If you strike it quick enough, the ruler will break near the table edge. What's going on? The Earth is covered in a layer of air that is nearly 80 miles thick and at sea level (the bottom) exerts or "pushes" hard almost 15 pounds of pressure per square inch. That means that a full sheet of newspaper laid out flat has nearly 9,300 pounds of air above it. When you break the ruler above, you are able to break it because of the "heavy" air pushing down on the paper while you quickly strike the ruler. At first, the table is pushing back on the paper, and if you move the ruler quick enough, other air around the edges of the paper can't get under the paper fast enough, so you are trying to lift that 9,300 pounds with the ruler! Some air gets under the paper, but not enough, so the ruler breaks. | ||
| 1. By doing the experiment, we may realize _____. | ||
[ ] | ||
| A. that air exits everywhere B. why there are directions C. that we live with air pressure D. how air helps on the earth | ||
| 2. How many steps are there in this experiment? | ||
[ ] | ||
| A. 2 B. 3 C. 4 D. 5 | ||
| 3. The underlined word "exert" probably means _____. | ||
[ ] | ||
| A. cover completely B. advocate actively C. influence gradually D. press heavily | ||
| 4. The ruler breaks under a quick strike mainly because of _____. | ||
[ ] | ||
| A. the air pressure on the newspaper B. the heavy weight of the newspaper C. the heavy weight of the flat table D. the strong power used on the ruler |
