一道英语选择题.求教come and join us,jenny.I am sorry,but i am really busy now ,if I -----time ,I would certainly go.A will have B have had C had D have

问题描述:

一道英语选择题.求教
come and join us,jenny.
I am sorry,but i am really busy now ,if I -----time ,I would certainly go.
A will have B have had C had D have