2 - Phrasal verbs ( run into, go back )

Run into - means that you come across someone or a situation...colliding with someone

Example: I ran into Monica while shopping for clothes.

to hit someone or something while driving, causing an accident

Example: A truck ran into me at the stop lights this morning.

to be in a situation

Example: I always run into those kind of situations when I think negative. 

to start to have problems

Example: Our project ran into problems when we started losing funds. 

run into

I saw a tiger in the forest. Children start running into the house.
I recorded a OVNI in the video. it run into the mountain. - You cannot say an object performed an action...in this case it is an inanimate object, so it does not make sense to say that the video ran into the mountain.
i'm running along the central park.

go back

-to a place

I want to go back to Brazil. 

-to a state of being, emotion

I want to go back to the person I was before. Positive and calm.

-to retrieve something

Can you back to your house and get your car keys? 

Go back to the last computer screen because that is the article that we need to read. 

You could go back to your school. ----> Excellent!

3 - Phrasal verbs ( check out, go off )

check out
Tem varios sentidos.

Primeiro, se voce quer dizer emprestar um livro da biblioteca.

Example: I am going to check out a book from the library. 

Segundo, dar uma olhada em alguma coisa.

Ex: I am going to check the movie out since you told me it was really good. 

I am going to check out this new restaurant in town.

Pode ser tambem de um sentido promiscuous.

Ex: Hey check that guy out. He's hot.

Terceiro, said de um hotel...do sentido que vc vai devolver as chaves e deixar o hotel 

Example: I need to check out of the hotel by 2:00 p.m.

The police check out your luggage ? Did the police check your luggage? Check out is wrong to use because it implies that the police is looking at the object sexually or promiscuously...
it before send the stuff, Please, check out all stuff. 

Before sending the stuff, please check if you have all that you need.

ir before parking your car, check out is allowed to park.

Before parking your car, check if parking is allowed. 
The enginner will check out project.

Good...except enginner - is spelled engineer. 

go off

Primeiro sentido e que alguma coisa para de funcionar ou ativar...

The alarms go off at night.

The lights go off automatically when the office is empty.

Segundo pode dizer basear  em alguma coisa

You can't go off what she says and bas your decisions like that.

I'm going off my car. I am going to my car. 
The man is going off the store. I am going to the store. 
I saw the police going out of the police station. 
I go off my country tomorrow later of my lunch. doesn't make sense.