"se puede" or "se pueden" followed by an infinitive
What are the grammatical rules that govern the "passive reflexive" use of "se puede" or "se pueden" followed by an infinitive ? From looking at the two sentences shown below; it appears that the object pronoun "se" is appended to the end of the infinitive. Is that the case ? And, if so, is this optional or required ?
Los científicos calculan que en torno a 3.700 casos de este tipo de cáncer podrían prevenirse al año.
Podría decirse que son como las estrellas: inalcanzables, pero marcan el camino.
The placement of the se is optional. It can be appended to the verb infinitive or placed before the auxillary verb
I'm not sure about the passive-reflexive term, however.
In the first sentence I agree in the passive part of the term.
that...this type of cancer could be prevented...
passive because the subject of the clause is the receiver of the verbs action.
to be reflexive the cancer would have to be preventing itself. It must be both the doer and receiver of the verb action. I think the doer of the preventing isn't mentioned. I would say that it is impersonal-passive which is a term that one of our other foreros has used here in this forum. In the impersonal construction the doer of the action is unknown. Se habla español aquí. Spanish is spoken here. We aren't told by whom...impersonal.
In the 2nd sentence:
It could be said (by whom?) One could say...exact same argument, but even clearer. I'd call it impersonal, passive se.