Don’t disturb me. I letters all morning and have written ten so far.
A. have written
B. am writing
C. was writing
D. have been writing
网友回答
A. have written
B. am writing
C. was writing
(答案→)D. have been writing
解析：句意：不要打扰我，我整个早晨一直在写信，到目前为止已经写了十封信。因为有all morning强调动作一直在进行，故用现在完成进行时，故选D。