_______it comes to traffic rules, I often come across such cases ________the local drivers obviously know them but won’t follow them.

A. If; why             B. As; which       C. Once; as          D. When; where

______it comes to traffic rules, I often come across such cases ________the local drivers obviously know them but won’t follow them.

A. If; why             B. As; which       C. Once; as          D. When; where

_______it comes to traffic rules, I often come across such cases ________the local drivers obviously know them but won’t follow them.

__________ it comes to traffic rules, I often come across such cases __________ the local drivers obviously know them but won’t follow them.

A. When; when           B. That; when          C. When; which      D. When; where

________ it comes to traffic rules, I often come across such cases ________ the local drivers obviously know them but won't follow them．

1. A.
   If; why
2. B.
   As; which
3. C.
   Once; as
4. D.
   When; where