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