-----Have you finished your position already, Jack? ----Yes, I it within half an hour.
A. have finished
B. finish
C. finished
D. had finished
网友回答
A. have finished
B. finish
(答案→)C. finished
D. had finished
解析：考查时态：句意：--杰克，你已经完成作文了吗？--是的，我半个小时就完成了。因为时间是过去的半小时，所以用一般过去式，选C。