The glass doors have taken the place of the wooden ones at the entrance, __ in the natural light during the day. A. to let b. letting c. let d. having let
―I wonder if I can board the plane with this return ticket.（ ） ―There ______ be no problem. Your ticket is valid until the end of this month. A. must B. shall C. should
His essay, ____many times,was brief and to the point,and therefore won the first prize in the writing competition. A.polishing up B.having polished up
