Good morning, onirediperu.
A: Did Helen buy the car from Tom?
B: No. Tom bought the car from Helen.
A: Excuse me. It's very noisy in this restaurant. What did you say?
B: I said that Tom bought the car from Helen.
B: IT WAS TOM who bought the car from Helen!!!!
A: Oh, thank you.
When you get a chance, study so-called "cleft sentences." They help emphasize the part of the sentence that concerns you.
TOM BOUGHT THE CAR FROM HELEN:
It was TOM who bought the car from Helen.
It was the CAR that Tom bought from Helen.
It was HELEN from whom Tom bought the car.
Have a nice day!