Here is the addres. You should write to this address. (FORMAL)
Here is the address to which you should write.
Here is the addres. You should write to this address. (INFORMAL)
Here is the address (which) you should write to.
The book belongs to me. You were looking at it just now. (FORMAL)
The book at which you were looking belongs to me.
The book belongs to me. You were looking at it just now. (INFORMAL)
The book (which) you were looking at belongs to me
I couldn´t recognize the house. He lived in it. (FORMAL)
I couldn´t recognize the house in which he lived.
I couldn´t recognize the house. He lived in it. (INFORMAL)
I couldn´t recognize the house (which) he lived in
A travel agency has booked the hotel. Jim is going to stay in it. (FORMAL)
A travel agency has booked the hotel in which Jim is going to stay.
A travel agency has booked the hotel. Jim is going to stay in it. (INFORMAL)
A travel agency has booked the hotel (which) he´s going to stay in.
Those are the boys. Mike is hiding from them. (FORMAL)
Those are the boys from whom Mike is hiding.
Those are the boys. Mike is hiding from them. (INFORMAL)
Those are the boys (who) Mike is hiding from.
I don´t know the boy. They went with him. (FORMAL)
I don´t know the boy with whom they went.
I don´t know the boy. They went with him. (INFORMAL)
I don´t know the boy (who) they went with.
He didn´t get the job. He applied for it. (FORMAL)
He didn´t get the job for which he applied.
He didn´t get the job. He applied for it. (INFORMAL)
He didn´t get the job (which) he applied for
She is a tennis player. I played against her last year (FORMAL)
She is the tennis player against whom I played last year.
She is a tennis player. I played against her last year (INFORMAL)
She is a tennis player (who) I played against last year.
