There is a new problem _____ the popularity of private cars that road conditions need _____.

　 A．involved in; to be improved 　　　　　　　

　 B．involving in; to be improved

　 C．involving in; improving　　

　 D．involved in; improved

There is a new problem _______ the popularity of private cars that road conditions need _________.

[　　]

A．involved in; to be improved

B．involving in; to be improved

C．involving in; improving

D．involved in; improved

There is a new problem involved in the popularity of private cars_______ road conditions need to be improved.

A.that                   B.which                C.where                D.when