The cancer risks _____smoking have been well documented.

A. associating with          B. involved with             

C. involving with             D. associated with

 The cancer risks _____smoking have been well documented.

A. involved with        B. involving with           C. associating with       D. associated with

The cancer risks _____ with smoking have been well proved.

　 A. combined　 B. associated　 C. caused　 D. joined

The cancer risks ___________ smoking have been well documented

1. A.
   involved with
2. B.
   involving with
3. C.
   associating with
4. D.
   associated with