do not have to和unnecessary的区别~

to have unnecessary是什么词性? "please do not do unnecessary reten tion have to,must,do not need,needn't的区别 have to do和must的区别 not to do,和 don't do的区别, do not have和have not有什么区别啊 It's unnecessary for you to worry about _____(not have)the a have...to do stn和have...doing stn的区别 have to do 和have doing的区别 have doing sth 和 have to do sth的区别 缩写时not和don t的区别.如：We have to do it,although we ___.是填not还是do seem to do和seem to have done的区别