We are _______ a copy of our catalogue for your reference.

We are _______ a copy of our catalogue for your reference.
A、send
B、covering
C、closed
D、enclosing
【正确答案】：D
【题目解析】：send发送；cover覆盖；close关闭；enclose装入，附上
be动词are后面不能接动词原形，故排除选项A。句意：随函附上我方目录一份，以供参考。