15. In the coming years , there are about 10,000 square kilometers of the designated search area still ( ) by sonar equipment towed from ships.

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.

66、The guest team was beaten by the host team 2( )4 in last year's CFA Cup Final.

65、The local authorities realized the need to make( )for elderly people in their housing programmes.

64、The chairman of the company said that new techniques had( )improved their production efficiency.

63、The fact that the management is trying to reach agreement( )five separate unions has led to long negotiations.

62、We should always bear in mind that( )decisions often result in serious consequences.

61、The Olympic Games( )in 776 B.C.in Olympia, a small town in Greece.

60、The scientists have absolute freedom as to what research they think it best to( ).