it的所有用法总结全部答:该句型中adj若为important,necessary,natural,possible,strange,vital,essential等可改为从句,从句用should+动词原形。.Eg:It’sverydangerousforchildrentoplaywithfire.ItisimportantforustolearnEnglishwell.(=Itisimportantthatwe(should)learnEnglishwell.)③ It+be+V-ed(reported,believed,said, suggested?...