He commanded that roads be built to link castles across the land.等于：

He commanded that roads should be built to link castles across the land.

难道网友忘记了那几个表“建议、请求、命令”的动词，接从句时句子用should + 动词原形，且should 可以省略吗？

常用的几个动词：

insist, command, order, suggest, propose, advise, demand, require, request, desire