has or had

[Casiopea]

A: Did you kill him?
B: Yes. I did. (OK)
Note, If the Question has "Did" then the answer tends to have 'did', but not always,

A: Did you kill him?
B: I have killed him. (OK)

A: Did you kill him?
B: I had killed him. (Needs a second event.)

A: Did you kill him.
B: I killed him after he had harmed so many human beings.

Note,
1st event: He harmed. => Past Perfect: He had harmed.
2nd event: I killed him. => Simple Past: I killed him.

[jack]

Why does "had" require a second event? i know this is a rule but why?

So if i use "have" with a second event, is it wrong? How do i know if it is a second event?

[Casiopea]

Originally Posted by jack

Why does "had" require a second event? i know this is a rule but why?

So if i use "have" with a second event, is it wrong? How do i know if it is a second event?

The Past Perfect (i.e. had -ed/-en) connects two events that happened in the past. Let's say, for example,

You ate dinner and you called a friend.

Notice the conjunction and in the sentence above. It joins the two sentences 'You ate dinner' + 'you called a friend. Let's say 'ate' happened before 'called'. In order to express that as a sequence of events, use the Past Perfect.

Here's a trick to the Past Perfect:

Step 1) First I a) _______, then I b) _______. (Two Events: a) and b))
Step 2) First I (past perfect), then I (simple past).
Step 3) First I had eaten dinner, then I called a friend.

Reword: Use 'before'
I had eaten dinner before I called a friend.

Reword: Use 'after'
I called a friend after I had eaten dinner.

All the best, :D

[jack]

So if i use "have" with a second event, is it wrong?

First I had eaten dinner, then I have called a friend. <--incorrect? why?

First I had eaten dinner, then I had called a friend. <--incorrect? why?

I called a friend after I have eaten dinner. <--incorrect? why can't i use have?

[Francois]

Basically you use present perfect/past perfect when you're actually interested in the fact and its consequences, rather than when it happened.

Eg.:

I had eaten dinner before I called a friend.

We don't care when exactly you ate your dinner, what's important in this sentence is that you had your dinner before another event (here: your calling a friend). The fact that you had eaten your dinner has presumably some impact on the time you called your friend (eg. you won't call him to go to the McDonald's).
Another example: I have lost my keys. We don't really care when I lost them, but rather that it's annoying now. However, if I add 'yesterday' for instance, the past simple is mandatory: 'I lost my keys yesterday'.
Back to the consecutive events examples (first...then), the second part helps locating the situation in time, thanks to the past simple. We now that the described situation took place when you called a friend of yours.

First I had eaten dinner, then I have called a friend. <--incorrect? why?
First I had eaten dinner, then I had called a friend. <--incorrect? why?

The problem is that we expect a past reference so that we know when you had eaten dinner. Unfortunately, the second part "I've called a friend (of mine)" doesn't help. So you end up with two events that are not bound to any specific moment -- wrong.

Again:

I have lost my keys
=> important now
I had lost my cellphone when the accident came about.
=> important when the accident came about.

FRC

[jack]

I have had this problem before. <--does this mean I had this problem before and now I still remember it?

[Francois]

Yes. You probably experience the same pb again, and you remember that you've already run across it before. Close link with the present + we don't really care when exactly you had the pb the 1st time => perfect tense.

FRC

[jack]

"I have never seen you drive before." <--correct? why?
"I have never seen you drove before." <--incorrect? why? how do i know if it is "drive" or "drove"?

[Francois]

"you" is an object pronoun here, so you could say:
"I've never seen her drive before"
The verb is in infinitive form, so 'drove' (past simple) is not correct.

FRC

[jack]

"I should of went to the mall." <--is "of" used incorrectly here? If not, why?
"I should have went to the mall." <--correct?