27.During the ()two decades， research has greatly expanded our knowledge about the sleep and dreams.( )

48.Riding on a bus without paying the fare()cheating the bus company.

47.() it is a good thing I did not get that post I applied for， though I must admit that I was disappointed at the time.

46.The rope ()( )when I pulled on it.

45.If you ()in taking this attitude， we＇ll have to ask you to leave.

44.To continue to oppose is to hold ()

43.What do you ()to do about the problem now that this solution has failed.

42.It is highly desirable that a new president ()( )for this college.

41.His great intelligence will () him to get a scholarship to college.

40.The quarrel()( )in a misunderstanding.

39.We must ()that the telegram arrives in time.