Like the stone of Roman wall, which were held together both by the regularity of the design and by that peculiarly powerful Roman cement, so the various parts of the Roman realm were bonded into
a massive, monolithic entity by physical, organizational, and psychological controls.
解答如下
（1）介词短语作状语：Like the stone of Roman wall
（2）非限制性定语从句：which were held together both by the regularity of the design and by that peculiarly powerful Roman cement
（3）句子主语部分：so the various parts of the Roman realm were bonded into
a massive, monolithic entity by physical, organizational, and psychological controls.
（4）主句是个被动语态的句子,而且带有一个介词短语,然后短语后,有一个非限制性定语从句修饰,
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