这是虚拟语气的一种情况.
在建议,要求,命令,想法后的动词后的从句里,用should + 动词原形,should 可以省略.如 advise,agree,command,decide,demand,determine,grant,indicate,insist,order,prefer,propose,request,require,stipulate,suggest,urge,vote.
例:She had requested that the door to her room be left open.