decide+doing or decide+to do

decide [] vi.,vt.决定；断定；判定
[教用法]1.decide to do：Last week,a group of Class 3 students decided to go to the museum in the centre of the town.上星期,三班的一些学生决定到位于镇中心的博物馆去.
2.decide that...：When the winds started to get strong,the family decided that it was not safe to remain in the house.当风势开始加强的时候,这家人认定,继续呆在房子里是不安全的.
3.decide + 疑问词 + to do：We must decide which one to buy.我们一定要定下来究竟买哪一个.
4.It is decided that...：It is decided that we should start tomorrow.已经决定我们明日出发.（注：这种从句要用虚拟语气.）