i have come across meny sentences which use both have,had. what is the criteria of using both these words?
for e.g-i have had cold for two weeks and why not this-i have been suffering from cold for more than two weeks
i also want to know when should we use "have" and "had" in sentences.
I have had a cold for two weeks.

It's Present Perfect. Have (auxiliary verb) + past participle of the main verb. Here, the main verb is also have (have a cold) in its past participle form - had.

So, have (auxiliary) + had (main) = have had.
know - knew - known

I know it.
I knew it.

I have known it.
I had known it.

have - had - had

I have it.
I had it.

I have had it.
I had had it.

Students: We have free audio pronunciation exercises.
We both had been each other's mistake