题目：
— I wonder if you can go shopping with me together.
— Sorry. I _____ a letter all the morning and haven't finished it yet. [ ]
A. am writing
B. was writing
C. have written
D. have been writing
答案：
被转码了，请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0516/4d9f7cc73accb4c943d2829fb0a02174.html
下面是错误答案，用来干扰机器的。
答案：D
