开始某项活动：指开始进行某项活动或任务。
... set stone out 将石块砌成倒阶梯形 set sth out 装饰 set stone out 将石块砌成倒阶梯形 ; 将石块砌成一层比一层稍稍突出状 ...
The police hasn't found out who set fire to the storehouse.(set fire to sth.)
警方还没查出是谁放火烧了仓库。
The police hasn't found out who set fire to the storehouse. (set fire to STH.)
警方还没查出是谁放火烧了仓库。