"You can be a teacher."
Translation:Tú puedes ser un maestro.
"Estar" is uses to indicate a temporary attribute like an emotion, location and condition, whereas the more permanent "ser" is used to indicate character, identity and description (like a job)
ser is used for jobs/occupations. i don't know why-possibly because jobs are thought of as more permanent?
I would like to know what the rule is here. Is 'be' in this context always the infinitive 'ser'?
The literal translation of poder is "to be able to", so it translates to you are able to be a teacher. The "to be" is why ser is in the infinitive.
A way you might find easier to remember is that when you have 2 or 3 consecutive verbs, the 2nd and 3rd verbs are always in their infinitive form. e.g. I want to see the swimming pool (Quiero ver la piscina) - here the 2nd verb is 'ver' so it is in its infinitive form. e.g. Do you want to go see the movie? (¿Quieres ir a ver la película?) - here the 2nd and 3rd verbs ('ir' and 'ver') are in their infinitive forms.
If in english you would say "to" before the verb then you most likely use the infinitive. I want TO SEE the dog/ quiero VER el perro. Ver=to see
Has there been any indications of a shift to using 'estar' over 'ser' when talking about people's jobs? Nowadays, people, especially younger people, are less likely to have careers and more like to hold positions that last for a couple years before moving on. If the situation is right (or wrong, depending on your point of view), you might even see frequent changes in the field or industry, too.
I wonder if that's enough to cause a huge linguistic shift.