There is/There are

"There is" y "There are" quieren decir "Hay" en español. "There is" es singular y "There are" es plural.

There is a book. (Hay un libro.)*
There are books. (Hay libros.)

*Se puede hacer una contracción de "There is" a "There's". No se puede hacer una contracción de "There are."

El negativo es "There is not" y "There are not" y sus contracciones.

There is not a book. - There isn't a book.
There are not books. - There aren't books.

Para formar una pregunta nada más cambiamos el orden de las palabras.

Is there a book?
Yes, there is.
No, there isn't.

Are there books?
Yes, there are.
No, there aren't.

invitar
transitive verb
1. (convidar)

* invitar a alguien (a algo/a hacer algo) -> to invite somebody (to something/to do something)
* me han invitado a una fiesta -> I've been invited to a party
* me invitó a entrar -> she asked me in

2. (pagar)

* te invito -> it's my treat, this one's on me
* invitar a alguien a algo -> to buy somebody something
* me invitó a una cerveza (food, drink) -> he bought me a beer
* te invito a cenar fuera -> I'll take you out for dinner

intransitive verb
3. to pay (pagar)

* invito yo -> it's my treat, this one's on me
* invita la casa -> it's on the house

4. (incitar)

* invitar a algo -> to encourage something
* este sol invita a salir -> the sun makes you want to go out