在40所高校研究生会参与的一个论坛上,300余名博士生向十一届全国人大代表发表公开信,建议全国人大代表们联合向 “两会”提交一份关于加快《住宅法》立法的议案。博士们的行为体现了（  ）

    Will the sky ever fall? The answer is no. But if it1, there's no need to be afraid!

    Chicken Little is an American cartoon film. It's very popular around the world. Its story teaches us: don't worry too much in your2.

    One day Chicken Little is in the forest when an acorn（橡果）falls on his head! This makes him3 . He thinks a piece of the sky is falling!

    He can't wait to tell4about it. They run for their lives!

    When people5the truth, no one likes Chicken Little. They laugh at him. He gets a bad name in the town. It's time for him to change others'6.

    Chicken Little begins to play baseball. He is not bigger than a ball,7he plays it very well! He helps his team8. Now they think he's great.

    Just then, a spaceship really does fall from the9! The aliens （外星人）have bad plans. Once again he must tell people about it.

    Will he get help from his friends in the town? Can he show himself a /an 10 person? You will get the answer from the cartoon film.

如图所示，左侧为一个半径为R的半球形的碗固定在水平桌面上，碗口水平，O点为球心，碗的内表面及碗口光滑．右侧是一个固定光滑斜面，斜面足够长，倾角θ=30°．一根不可伸长的不计质量的细绳跨在碗口及光滑斜面顶端的光滑定滑轮两端上，线的两端分别系有可视为质点的小球m₁和m₂，且m₁＞m₂．开始时m₁恰在右端碗口水平直径A处，m₂在斜面上且距离斜面顶端足够远，此时连接两球的细绳与斜面平行且恰好伸直．当m₁由静止释放运动到圆心O的正下方B点时细绳突然断开，不计细绳断开瞬间的能量损失．