We are required to write an essay for the course.I______about ha

We are required to write an essay for the course.I______about half of mine so far.
A、write
B、have been writing
C、wrote
D、have written
【正确答案】：B
【题目解析】：此题考察的是完成进行时。句子意思是我们要求写篇课程论文。到现在为止我一直写了有一半了。根据第一句的are可判断为现在时，so far是到现在为止用完成时，根据句义到现在一直在写论文，所以用现在完成进行时。