It was insisted that the man▁▁to prison because he committed

e sent
insist + that引导的宾语从句
1）如果insist翻译为“坚持说/坚持认为”,和主句时态保持呼应.
如：She insisted that she was right.
2）如果insist翻译为“坚持要求/坚持主张”,即that从句的动作当时尚未发生的话,则宾语从句使用虚拟语气,即从句“should + 动词原形”构成,should可以省略.
如：He insisted that she (should) say sorry to him frist.