be necessary for和be necessary to 有何区别

be necessary for和be necessary to 有何区别 be necessary for和 be necessary to的区别 此题中 be necessary for 和 to的区别,为什么不能用to啊 be necessary be necessary for的用法 "To be taken when necessary. be not necessary= Necessary+for还是to? be dangerous to & be dangerous for 有何区别? A site had to be found for it.It was necessary ____ for it important和necessary区别 句子改写,1 it will be necessary for you to see a doctor.（改为一般疑问句