根据问句，选择适当的答语。(20分)
(  )（1）What are you doing?
(  )（2）What is Sam doing?
(  )（3）What is she doing?
(  )（4）Are you writing a letter?

A．She's taking pictures.	B．I'm talking to my friend.
C．He's playing with his car.	D．No, I'm not.