| 如图所示，倾角为θ的固定光滑斜面底部有一直斜面的固定档板C．劲度系数为k1的轻弹簧两端分别与质量均为m的物体A和B连接，劲度系数为k2的轻弹簧一端与A连接，另一端与一轻质小桶P相连，跨过光滑的滑轮Q放在斜面上，B靠在档板C处，A和B均静止．现缓慢地向小桶P内加入细砂，当B与档板C间挤压力恰好为零时，小桶P内所加入的细砂质量及小桶下降的距离分别为（ ）
B．2m、 C．2msinθ、 D．2msinθ、 |
答案：D
| 选用所给句子完成对话。 | |
| A: We have to meet the others at 8: 30 at the reserve (自然保护区), don't we? B: (1) ________ A: Do you know how to get there? B: (2) ________It'll take us about two hours to get there by bus. A: (3) ________ B: It's an area that protects lots of different animals. A: (4) ________ B: I'm not really sure. I know there are many different kinds of birds there and I'm going to take my camera with me. A: (5) ________ What clothes are you going to wear? B: Well, if it's wet, I'll wear my strong shoes and take my raincoat with me. A: So I will.
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