--Mr. Li, I found a watch on the playground.

              --You should try to find out _________

 A. whose is the watch     

 B. who is the owner of the watch

C. whom does the watch belong to

--- Mr. Li, I found a watch on the playground.

--- You should try to find out ______

A. whose is the watch　

B. who is the owner of the watch　

C. whom does the watch belong to

Do you know ________?

1. A.
   whose pen is this
2. B.
   whom does the pen belong to
3. C.
   whose pen this is
4. D.
   whose is this pen