Do these sentences work(final confirmation)

Hi,

I didn't know if I have to do it or not.

I didn't know if I had to do it or not.

I don't know if I have to do it or not.

I don't know if I had to do it or not.

Which ones are right or wrong?

#1 sounds wrong. The others are fine. They have different meanings, of course.

I don't understand how the last one could be correct? Shouldn't the verbs be in the same tense?

pleasehelpI don't understand how the last one could be correct? Shouldn't the verbs be in the same tense?

What keeps confusing me is the, "Did that happen to you too?"

Usually if a sentence starts with did the verb following it would always be the base form.

So with these sentences I don't know what is right or wrong.....

Hi,

I didn't know if I had to do it or not.

There are two clauses here, and you have to look at each clause separately.

In the maim clause, the verb that follows 'didn't' is 'know', which is the infinitive base form.

'If I had to do it' is a separate subordinate clause. The inflected verb in it is 'I had'.

"To do'

Hi,

I don't know if I had to do it or not.

Shouldn't the verbs be in the same tense?

No. I told you about that.



eg Today I don't know if I had to do something yesterday.



Clive