Tree and flowers are on either bank of the river.
A.either B.both C.any D.every
两边都有花木,either 是任何一边,每一边.
There are tall buildings on _every side of the playground.
A.all B.either C.every D.none
操场两边都有高楼.如果用all,后面的side则应该用复数了：sides； either 是两边,操场有四边,所以不是它； none是否定,这样用很别扭.如果没有高楼,何不说：there is no tall buildings on any side of the playground?