3.ask sb (not ) to do sth 要求某人(不要)做某事 4.used to do sth 过去常常做某事 5.decide to do sth 决定做某事 6.help sb (to)do sth 帮助某人做某事 7.make a difference to 对...产生影响 8.make it possible for sb to do sth 使得做某事对某人来说是可能的 ...