问题补充：
Hearing the interesting story, all the people present.
A. burst into laughing
B. burst into laughter
C. burst out laugh
D. burst out laughter
答案：
A. burst into laughing
(答案→)B. burst into laughter
C. burst out laugh
D. burst out laughter
解析：句意：听到有趣的故事，所有在场的人都突然笑起来了。词组“突然笑起来”可以是burst into laughter也可以是burst out laughing，所以选B。
