They are ( )these books in the box.A.puts B.put C.to put D.putting

题目

They are ( )these books in the box.A.puts B.put C.to put D.putting
选择,最好帮我讲解一下.

答案

D
他们正把这些书放到盒子里.现在完成时.are提示了,故用are putting