Do you know that smoking and drinking has become a ________ problem among teenagers, which worries many parents and teachers?

1. A.
   popular
2. B.
   typical
3. C.
   daily
4. D.
   traditional

Do you know that smoking and drinking has become a _____ problem among teenagers, which worries many parents and teachers ?

A．popular          B．typical         C．daily           D．traditional