Every means ____tired?选什么?为什么?

Every means ____tired?选什么?为什么? Every possible means ___.was tried has been tried.为什么不能选 Was every后面不是加单数可数名词,为什么要说every means 而不能说every mean? try every possible means 为什么是means 不是mean.不是说有every each修饰时用 by every means every possible means the sign means“ ”（danger）.填什么,为什么 Red means good luck means为什么+s? .Every means tried____ but without much result. Every means has been tried since Every means ----prevent the water from -----. Every possible means -----,but none proves successful.