I _______the number down ____a piece of paper.

问题描述:

I _______the number down ____a piece of paper.
A.am writting,on
B.am writting ,in
C.am writing ,on
D.am writing,in

“写”的-ing形式不用双写t
所以排除A,B.
又,把……写在报纸上用介词in,这是固定搭配.所以选D