were to do,表示对将来的虚拟
最老早的规矩是虚拟里面没有was的
he/she/it were单数也用were的
后来变简单了,单数可以的话可以用was
当然你用were是绝对不会错的
只有If I were you,永远要这么说,不能变
所以If he was to 也可以,但是不正规