Ⅰ. 请根据句意，用介词of 或for填空，补全句子
【小题1】It is necessary __________ us to take action to reduce the air pollution.
【小题2】It is kind __________ you to help me with my lessons.
【小题3】It is important __________ students to have enough sleep every day.
【小题4】It is dangerous __________ children to play with fire.
【小题5】It is silly __________ her not to forgive others for their mistakes.