28. The ( ) cited study suggested that parental involvement in homework can boost a student ' s academic performance.

51、You ( ) Jim anything about it. It was none of his business.

50、I was very much put ( ) by Mark's rude behavior; it really annoyed me.

49、My mother can't get ( ) because she has rheumatism(风湿病).

48、There ( ) nothing more for discussion, the meeting came to an end half an hour earlier.

47、Do help yourself to some fruit,( ) you?

46、The central provinces have floods in some years, and ( ).

45、This is an illness that can result in total blindness ( ) left untreated.

44、Acute hearing helps most animals sense the approach of thunderstorms long before people ( ).

68、As a developing country, we must keep( )with the rapid development of the world economy.

67、The police let him go, because they didn't find him guilty( )the murder.