Question

--- What are you doing?  

--- I ______  a letter to my pen pal.

1. A.
   write
2. B.
   am writing
3. C.
   writes
4. D.
   am write

Answer 1

B
此题考查现在进行时态。根据问句的意思你正在干什么，可知答语也应用现在进行时态，所以选B。