in the 1980s,in the 1980's和in 1980s的区别

in the 1980s,in the 1980's和in 1980s的区别
in the 1980s,in the 1980's和in 1980s的区别

in the 1980s,in the 1980's和in 1980s的区别
in the 1980s 和in the 1980's（一般用它）在二十世纪八十年代 算是个独立短语了,固定搭配
in 1980s 也是在二十世纪八十年代 做不及物动词后名词

in the 1980s是指在20世纪80年代
in 1980s 说实话，我是真没见过这么用的
in the 1980's应该是指在20世纪80年代的·····
后面应该还加点什么东西···