[Grammar] Hand't Vs Haven't

Dear Sir/Madam,

What is difference between two sentences.

I hadn't thought about that.

I haven't thought about that.


Yours Faithfully,

The first is in the past perfect tense; the second is in the present perfect tense.

I have already know this ! but what is difference in the meaning ?

kalhori said:

I have already know this ! but what is difference in the meaning ?

Click to expand...

Well, it has the usual meaning difference between any two sentences with each of these tenses. If you are asking what is the meaning difference between the past perfect and present perfect tenses, this is something you need to study. It's impossible to give a proper response to your question in less than a few pages. There are many sites on the web that already explain this in some detail.
Here are some examples:
http://www.espressoenglish.net/difference-between-present-perfect-and-past-perfect-in-english/
http://www.englishpage.com/verbpage/presentperfect.html
http://www.englishpage.com/verbpage/pastperfect.html

If you want to read those, and give us your understanding of those sentences, we can respond in a useful way. Otherwise, we'd have to assume that you know nothing about the tenses and basically re-write one of those pages - which are already there.

These are the usual thinking processes with these two sentences. Of course, there can be many other thought processes.

I hadn't thought about that. (In retrospect, I could have thought about it in THAT other way.)

I haven't thought about that. (I really didn't take the time or effort to think about that.)


--lotus