Don’t disturb me. I letters all the morning and have written ten so far.
A. write
B. was writing
C. have written
D. have been writing
网友回答
A. write
B. was writing
C. have written
D. have been writing
解析：考查时态。本题的关键词是时间状语all the time一直。该时间状语通常与现在完成进行时连用。句意：不要烦我，我一直在写信，到目前为止已经写了10封了。现在完成进行时表示一直在做某事，强调动作的持续性和反复性。故D正确。