_____ private cars are bringing us convenience, they may also cause more traffic accidents and pollution.

       A．While      B．As           C．If            D．Since

_____ private cars are bringing us convenience, they may also cause more traffic accidents and pollution.

A.While    B.As      C.If       D.Since

_____ private cars are bringing us convenience, they may also cause more traffic accidents and pollution.

A.While    B.As      C.If       D.Since

_____ private cars are bringing us convenience, they may also cause more traffic accidents and pollution.

A.While    B.As      C.If       D.Since

_____ private cars are bringing us convenience, they may also cause more traffic accidents and pollution.

A. While    B. As      C. If       D. Since