非企业性单位如果经常发生增值税应税行为，并且符合一般纳税人条件的，可以由税务机关认定为增值税一般纳税人。 ( )

—I hear Mr. Zhang has gone to Beijing for a meeting.

—Really? Do you know when he ______?[ ]

A. leaves

B. was leaving

C. has left

D. left