I’m afraid I won’t be available then.I _____ a friend off at three this afternoon.

题目

I’m afraid I won’t be available then.I _____ a friend off at three this afternoon.
A.see B.am seeing C.will see D.will be seeing
这里为什么填D不填A,一般现在时不是可以表示安排好的将来的事吗?

答案