问题补充：
They were busy with each other the time.
A. too; talking; to forget
B. so; talking; that they forgot
C. so; to talk; that they forgot
D. too; to talk; to forget
答案：
A. too; talking; to forget
(答案→)B. so; talking; that they forgot
C. so; to talk; that they forgot
D. too; to talk; to forget
解析：句意：他们忙于相互交谈以致忘了时间。Be busy doing sth忙于做某事；too···to太···而不能。So···that如此···以致。所以选B。
