语法专练（动词-ing形式）
【小题1】At this moment the doorbell rang, ______________（announce）the arrival of our guests.
【小题2】The factory owners had the machines ______________（run） all night long to earn money as much as possible.
【小题3】Like ancient sailors, birds can find their way ______________（use） the sun and stars.
【小题4】The book ______________（lie）on the table doesn’t belong to me.
【小题5】The ______________（miss）boy was last seen ______________（play）near the West Lake.
【小题6】His letter poses a number of ______________（puzzle）questions.
【小题7】Mr. Li, ______________（work）as a teacher for almost 40 years, is now doing voluntary work in our community.
【小题8】He related some ______________（amuse）stories about his students to his friends.