It was with great joy ________ he received the news that his lost daughter had been found.

A．because

B．which

C．who

D．that

目前，长江沿江地带拥有很多城市，其中_______、南京、_________、重庆四个特大城市，是区域的经济、文化和交通中心，对区域经济发展具有强大的_________和____________作用。