can you use "à" instead of na in this sentence like
"Eu preciso entrar à galeria" ??
No, "entrar em" is what you should use when you're talking about entering physical locations. "Entrar a" is used for other things - the first that came to my mind is "Entrar a horas", which by itself meaning "to arrive at work [enter your workplace] on time", but can replaced with a certain time:
- Entrei às nove [horas]. I started my shift at nine o'clock.
I think "I have to come in the gallery." I don't know whether or not that's correct so someone help.
First, you would say "go" if you, the speaker, are on the outside. You would say "come" if you are on the inside talking about entering from the outside (so an unlikely context). Example, speaker now in the gallery: "After I go out to McDonald's to get some lunch, I'll come (back) into the gallery to eat it." "Enter" can refer to both coming or going. Second, with verbs denoting motion you do have to say "into" and not "in."
Another note because there's more to this. You would say "come" if the person you are addressing is at the destination: "I am upstairs in the office right now, but I will come into the gallery (to meet you) in a few minutes." If the person addressed is not in the gallery, then you would say "go into."
"I need to enter into the gallery" lost me a heart. :(( Where's the logic???
"Enter" already contains in and of itself the idea of "going into" something, you "into" is not necessary and may seem rather redundant to some.
See a few correct uses of "to enter into" as a phrasal verb here: http://www.macmillandictionary.com/dictionary/british/enter-into.
I see this program translate precisar as to have to, but I always understood it should be translated as to need, and ter is to have. They tend to have the same meaning so it doesn't matter that much I guess but am I wrong?