on the fence

　　释义：

　　in a position of neutrality or indecision 保持中立，抱骑墙态度;to delay making a decision 未决

　　用法：sit/be on the fence

　　eg. You can't sit on the fence any longer - you have to decide whose side you're on.

　　你不能再骑墙观望了——你必须决定支持谁。