Which statement is grammatically correct?

Question 17 options:

Vas a lo mirar.

Lo vas a mirar.

Vaslo a mirar.

Which statement is grammatically correct?

Question 18 options:

Tenemos que verlo.

Tenemos lo que ver.

Tenemos que lo ver.

If it refers to a ticket, how do you say I am buying it ?

Question 19 options:

Yo la compro.

Yo lo compro.

Yo compro lo.

Yo compra la.