请教个语法知识.我英语语法很差.

问题描述:

请教个语法知识.我英语语法很差.
1、Every possible means has been tried,but none worked.
2、All possible means have been tried,but none worked.
为什么第一句中用has been ,第二句中用have been、?请分析下,
另外been前加has/have是现在完成时?

Every强调的是每个,用单数
All强调的是全部,用复数