Some of my friends are interested in science，but none of them can tell         

  A when UFOs will appear next time    B why do horses know the way

  C where was this kind of plant found   D how do elephants communicate

Some of my friends are interested in science，but none of them can tell         

  A when UFOs will appear next time    B why do horses know the way

  C where was this kind of plant found   D how do elephants communicate

Some of my friends are interested in science，but none of them can tell         

1. A.
   when UFOs will appear next time
2. B.
   why do horses know the way
3. C.
   where was this kind of plant found
4. D.
   how do elephants communicate