The passive paraphrastic is a verbal construction which indicates a sense of necessity or obligation (comparable to what you mean when you use debëo to mean "should").
sum + the future passive participle [gerundive]
1. Id faciendum est.
2. Iste imperätor ex urbe pellendus est.
3. Cernisne omnia quae tibi scienda sunt?
dative of agent:
Because the passive paraphrastic is inherently passive, you can't indicate agency through the subject. Up to now we've indicated agency in the passive voice with the ablative of personal agent. When you use the passive paraphrastic, however, you must use the dative of agent.
The dative of agent simply expresses the agent in the dative voice. For example:
Id mihi faciendum est. -
It must be done by me.
I must do it.
Iste imperätor ex urbe nöbïs pellendus est.
That (scurrilous) general must be expelled from the city by us.
We must expell that scurrilous dictator from the city.
Chapter Index / Passive Paraphrastic Drill