Long time no see!  

Long time no see! means ‘I have not seen you in a long time.’

Robin: Hi Jane, long time no see! Where have you been keeping yourself?

Jane: My new job is pretty demanding. I’ve got to work long hours almost every day. Anyway, nice to see you Robin.

I don’t mind

I don’t mind means ‘I have no objections’.

‘You may go and swim in the sea. I don’t mind.’

‘I don’t mind your smoking but you have to leave the room before you light that cigarette.’

It’s up to you    

It’s up to you simply means you are the one who has to make a decision.

Jacky: Should I buy laptop? What do you think?

Jane: It’s up to you. You’re the one who foots the bill.

Another piece of conversation is given below.

Vicky: I’m quitting my job.

Antony: What are you going to do then?

Vicky: I’m launching my own business. What do you think?

Amar: It’s up to you. You should know better than me.

That depends   

This expression is used when you cannot give a definite answer to a question.

James: Will you be able to come to the conference on Monday?

Peter: That depends. I might be able to come if I’ve no other business.

Another example is given below.

John: Do you enjoy watching films?

Mary: That depends on the kind of film I’m watching. I enjoy watching romantic comedies, but I’m not really into action flicks.