52. What was intended as a peaceful demonstration rapidly _____ into violence.

D degenerate

解释:
柯林斯字典里面写："If you say that someone or something degenerates, you mean that they become worse in some way"。就是所谓的“情况变糟，变坏，变差”等等。

顺便翻译一下这道题吧~
What was intended as a peaceful demonstration rapidly degenerated into violence.
原本计划好的一场和平示威立刻暴力起来。