convulsion|convulsions

他突然抽搐发作，身体剧烈痉挛起来。

He suddenly had a ___convulsion and his body jerked violently.

经济危机引发了社会的剧烈动荡。

The economic crisis triggered violent ___convulsions in society.

战争引发了整个地区的剧烈动荡。

The war triggered a violent ___convulsion across the entire region.