根据句意和汉语注释，写出单词的正确形式。
（1）As we know, oil always (漂浮) on water.
（2）He (点头) to me in greeting when I entered the room.
（3）We are very (自豪) that a pupil from our school has won the prize.
（4）They all hurried (往楼上) to see what was going on.
（5）There was (沉默) for a moment and then someone made a useful suggestion.
