Choose the suitable grammatical construction to complete each sentence.

Choose the correct option.

Lisa has got an old smartphone. She [buys|is buying|is going to buy] a new one. She [buys|is buying|is going to buy] a new smartphone next Saturday.

"[Are you going to visit|Are you visiting|Do you visit] the doctor?" — "Yes, I [am going to visit|am visiting|visit] him tomorrow at 8 am."