问题
单项选择题
如图所示，质量分别为mA和mB的物体A、B用细绳连接后跨过滑轮，A静止在倾角为45°的斜面上．已知mA＝2mB，不计滑轮摩擦，现将斜面倾角由45°增大到50°，系统保持静止．下列说法正确的是（）
A.细绳对A的拉力将增大
B.A对斜面的压力将减小
C.A受到的静摩擦力不变
D.A受到的合力将增大
答案
参考答案：B
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如图所示，质量分别为mA和mB的物体A、B用细绳连接后跨过滑轮，A静止在倾角为45°的斜面上．已知mA＝2mB，不计滑轮摩擦，现将斜面倾角由45°增大到50°，系统保持静止．下列说法正确的是（）
A.细绳对A的拉力将增大
B.A对斜面的压力将减小
C.A受到的静摩擦力不变
D.A受到的合力将增大
参考答案：B
| 阅读理解。 | ||||||
Timetable
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| 1. If you want to learn something about satellites (卫星), you should go to the Children's Palace on _______. | ||||||
| A. Sunday B. Wednesday C. Thursday D. Monday | ||||||
| 2. Mr. Brown can speak not only English but also ________. | ||||||
| A. Chinese B. Italian C. Japanese D. German | ||||||
| 3. The teacher who teaches computer science is from ________. | ||||||
| A. Italy B. America C. England D. China | ||||||
| 4. You may learn something about clone (克隆) from ________. | ||||||
| A. Mr.Browm B. Prof. Green C. Prof. Morison D. Dr.West | ||||||
| 5. The Technical English class may last for about ________. | ||||||
| A. 4 months B. 4 weeks C. 12 weeks D. 35 days |