be silly to do sth.= It's silly of sb.to do sth.还要例句的

be silly to do sth.= It's silly of sb.to do sth.还要例句的 be silly to do还是be silly doing Do not be silly be sure to do sth. be pleased to do sth be able to do sth be going to do sth be let to do sth? be sad to do sth. be made to do sth be obliged to do sth. be used to do sth. be late to do= be late doing sth be to do sth和will do sth的区别 be worth to do sth 还是be worth doing sth be scared to do sth还是be scared doing sth be surprised at sth.和be surprised to do sth. be glad to do sth 还是be glad doing sth