两道英语题目不懂其中语法（（）（）（）（））
1.It's very cold today.You'd better (not take off)your sweater.
2.The policeman told the children (not to play)football in the street.
1句、2句中为什麽一个为not do sth.还有一个.not to do sth
什么时候用not do sth.\not to do sth.有什么不一样?