问题补充：
In order to be for Christmas, all these gifts must be mailed immediately.
A. at one time
B. in time
C. at a time
D. in no time
答案：
A. at one time
(答案→)B. in time
C. at a time
D. in no time
解析：本题考查time短语。A. at one time曾经； B. in time及时； C. at a time每次几个； D. in no time立刻。句意：为了在圣诞节及时收到，所有这些礼物必须立刻寄出去。
