The audience when they heard the humorous story.
A. burst into laughing
B. burst out laughter
C. burst into laughter
D. burst in laughing
网友回答
A. burst into laughing
B. burst out laughter
(答案→)C. burst into laughter
D. burst in laughing
解析：考查短语：突然大笑起来burst into laughter = burst out laughing，句意：当他们听到这个幽默的故事观众们突然大笑起来。所以选C。