问题
不定项选择
在下列所述实例中，若不计空气阻力，机械能守恒的是[ ]
A．石块自由下落的过程
B．电梯加速上升的过程
C．抛出的铅球在空中运动的过程
D．木箱沿粗糙斜面匀速下滑的过程
答案
AC
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在下列所述实例中，若不计空气阻力，机械能守恒的是[ ]
A．石块自由下落的过程
B．电梯加速上升的过程
C．抛出的铅球在空中运动的过程
D．木箱沿粗糙斜面匀速下滑的过程
AC
| 阅读理解。 | ||||||||||||
| ||||||||||||
| 1. Who is the youngest of the people? | ||||||||||||
[ ] | ||||||||||||
| A. Daniel Radcliffe. B. Celine Dion. C. Bill Gates. D. Mark Twain | ||||||||||||
| 2. ______ people of the five people come from the USA. | ||||||||||||
[ ] |
| A. Five B. Two C. Three D. Four |
| 3. My Heart Will Go On is the name of a ______. |
[ ] |
| A. film B. book C. story D. song |
| 4. Thomas Edison died at the age of ______. |
[ ] |
| A. 81 B. 82 C. 84 D. 85 |
| 5. Who wrote Tom Sawyer? |
[ ] |
| A. Thomas Edison. B. Bill Gates. C. Celine Dion. D. Mark Twain. |