Play, often ______ as an activity for younger children, is still important in the social development of teenagers.

Play, often ______ as an activity for younger children, is still important in the social development of teenagers.

A．to see            B．seeing            C．seen             D．to be seen

Play, often ________ as an activity for younger children, is still important in the social development of teenagers．

1. A.
   to see
2. B.
   seeing
3. C.
   to be seen
4. D.
   seen

Play, often ________ as an activity for younger children, is still important in the social development of teenagers.

  A. to see                                   B. seeing                             C. to be seen                      D. seen