By

Is a preposition to express agency: “by” + agent.

• Express agency

• By + agent

  Agent is a person or the thing that does the action.

EXAMPLE

Last month I read a great book by Mario Mendoza.

The building was restored by the constructor.

It’s a stunning painting by Picasso.

1. My favorite book is by George Orwell its name is 1984.
2. My grandfather was checked by the doctor.
3. The class was taught by Cesar Cordero.
4. Mona lisa was painted by Leonardo DaVinci.

To

We can use “to” to refer to the recipient of the sentence or the indirect object, which essentially means the person receiving something, receiving an object.

• Refer to the recipient.
• Refer to the indirect object.
• To + Noun.

EXAMPLE

We’ll give this to your mother, not to you. Don’t insist, please.

• “your mother” who is the indirect object of the sentence. She is receiving something.