to make 是对的.to prevent fires （“预防火灾”）的目的是to make the environment safer,这里的to make the environment safer是做目的状语的,和to prevent fires并列.此处切勿受到prevent的干扰.另外,此处的不定...那道题和这道题不一样……我的多了个and哦。那此处的(to) make the environment safer 和to prevent fires并列关系，因为把to prevent fires去掉后意思基本不变。to是否要省略？可以省略，如：It’s necessary for us to read more and have more practice. He didn’t want to go on working but have a rest.