After describing the planned improvements, she went on how much they would cost.
A. to explain
B. explaining
C. to be explaining
D. having explained
网友回答
(答案→)A. to explain
B. explaining
C. to be explaining
D. having explained
解析：go on doing sth = 继续做同一事情，go on to do sth = 做完某事后续继做某事。