In the past, ice used to ______ used to ______ tbe air in a room.
A.be; coolB.be; coolingC.being; coolD.being; cooling在线课程A
本题同时考查use的本义用法及含有used的词组 。其正确句意应为：在过去，冰曾经被用来冷却屋子里的空气。将used to do sth.与be used to do sth.合二为一，则成了used to be used to do sth.。