如果用which则involving要改成involve,那么which在这里就可以指代murders, seven robberies和sixty other violent attachs,与句子的意思就不统一了.用these则表示these仅仅指代sixty other violent attacks,和前面的...多谢。这里的involving是不是修饰these，fights 是谓语。请帮分析and about sixty other violent attacks, most of these involving fights at parties.的语法。