问题
选择题
| 跟用手直接做功相比，使用滑轮组做功可以（ ） A．省力和改变力的方向 B．省力和省功 C．省力和提高机械效率 D．省力和省距离 |
答案
答案：A
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| 跟用手直接做功相比，使用滑轮组做功可以（ ） A．省力和改变力的方向 B．省力和省功 C．省力和提高机械效率 D．省力和省距离 |
答案：A
| Look and choose the proper sentences. 看图，选择合适的句子。 |
 1. ( ) |  2. ( ) |  3. ( ) |
 4. ( ) |  5. ( ) |  6. ( ) |
| A. An airplane is fast. B. — Mum, may I go on a trip to Beijing? — OK, Li Ming! You work hard in school. You may go. C. We go on a trip by train. D. Jenny and Danny arrive in Shijiazhuang on January 19th. E. I love to go on trips. F. Danny and Jenny leave Canada on January 18th. |