下面词语中没有错别字的一项是（   ）

某人在一星球上以速度v₀竖直上抛一物体，经t秒钟后物体落回手中，已知星球半径为R，那么使物体不再落回星球表面，物体抛出时的速度至少为（   ）

    I did something wrong today.

    While at the beach this afternoon. I met a boy called Bob We talked a lot. He said that it was fun playing on the cliffs (悬崖). I told him that I was not allowed to go near that place(Mum and Dad had always told me it was dangerous to play there). He called me a coward. I wanted to prove to him that I was just as brave, so I agreed to go with him.

    We wanted to make our way down to explore (探索)the area, so Bob started to climb down and I followed him. Unluckily, some rocks came down after us. One of them nearly hit my head. We could not get back up. We shouted and shouted for help, but for a long time no help came. I was really scared. I wanted to cry. Then, we heard some sounds. Someone had heard us. A woman tied (系 )a rope around herself while a man at the cliff top held the rope. She made her way down to save us.

    My parents were relieved (宽慰的)that I was unhurt, but they were angry that I had done such a risky thing. I apologized and promised that I would not do anything like that again.

(B)根据句意,在答卷对应题号的横线上,写出括号内所给单词的适当形式。