大概意思：
条例规定：只有医生或护士和斯密史医生邀请的那些人可以进入病房,其余人员一律不得入内.
the rule = 主语
says = 谓语
that.= that引导的宾语葱郁
nobody.those invited by dr.smith = 从句中的主语
go into the patient's room = 从句中的谓语+状语
供参考.可以继续追问.