问题补充：
I wish I could go to Mars one day.
A. a few days.
B. that day.
C. in one day.
D. some day.
答案：
A. a few days.
B. that day.
C. in one day.
(答案→)D. some day.
解析：考查固定短语。句意“我希望有一天我能去火星。”one day“（将来或过去）有一天”；a few days“几天”；that day“那天”；some day“将来或过去的某天”，相当于one day。故选D。
