I have to …

Question 1

I have to do something =

Answer 1

it is necessary for me to do it, I am obliged to do it

…I’ll be late for work tomorrow. I have to go to the dentist.
…Jane starts work at 7 o’clock, so she has to get up at 6

Question 2

The past (yesterday / last week etc.) is

Answer 2

had to …

…I was late for work yesterday.
…I had to go to the dentist

Question 3

In questions and negatives, we use

Answer 3

do/does (present) and did (past)

…Does Jane have to work on Sundays?
…Why did they have to leave the party early?

#
I have...I've got

Do you have a camera?’ ‘No, I don’t.’
or
‘Have you got a camera?’ ‘No, I haven’t.

Question 4

You can use must OR have to when you say what you think is necessary, when you give your OPINION

…It’s a fantastic film. You must see it.
or
…You have to see it.

Answer 4

When you are NOT giving your personal opinion, use have to (not must).

Compare:

…Jane won’t be at work this afternoon. She has to go to the doctor. (this is not my personal opinion – it is a fact)
…Jane isn’t well. She doesn’t want to go to the doctor, but I told her she must go. (this is my personal opinion)