【题目】Be sure to return __________ you are done!
A. shortly B. immediately
C. constantly D. momentarily
在线课程【答案】B
【解析】考查词性辨析。A. shortly立刻；B. immediately立刻，一……就……；C. constantly不断地；D. momentarily随时地。A/B/D都可用作副词“立刻，马上”，但只有B项可以作连词，而空格后为从句。句意：你一完事，一定要回来！故选B。