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I have visited her long back

I had visited her long back(Is this wrong tense kindly explain why)

The demolition of old structure was an unfortunate event, which should have never taken place.

The situation would have been out of control, if police had not fired tear gases.

I have spoken to you regarding this in the past also

I spoken to you regarding this when we met in the conference two years ago
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I have visited her long back "long back" is not correct. Perhaps you mean "a long time ago"? In that case, the present perfect is not the best tense to use. You can say, "I have visited her recently."

I had visited her long back (Is this wrong tense kindly explain why) The tense (past perfect) is OK, but "long back" is not.

The demolition of the old structure was an unfortunate event, which should have never taken place.

The situation would have been out of control, if police had not fired tear gases.

I have spoken to you regarding this in the past also

I (missing auxiliary) spoken to you regarding this when we met in the conference two years ago
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I (missing auxiliary) spoken to you regarding this when we met in the conference two years ago

shall i write

I have spoken to you...... or I had spoken to you...which one is the correct?
I haven't seen him for three years.
He hasn't smoke fr two weeks.
When did he arrive?
He arrived at 2.00.
Did you lock the door before you left the house?
I have read his books when I was at school. Ienjoyed them very much.
I have never drank whisky.
I have written the letter but I can't find a stamp.
I just cleaned them.
I left home at 8.00 and got here at twelve.
I have done this sort of work when i was an apprentice.
He has just went out.
He went out ten minutes ago.
Did you have breakfast yet?
Yes, I had it at 8.00.
I met him last June.
Did you see the moon last night?
The concert has began at 2.30 and lasted for two hours. Everyone enjoye it very much.
Please check if the tenes are correct. I don't know when to use Present perfect and when the simple past.
Thank you. Emotion: smile
CreativeguruI (missing auxiliary) spoken to you regarding this when we met in the conference two years ago

shall i write

I have spoken to you.. or I had spoken to you...which one is the correct?
Both are possible. The choice depends on the context.
Regards,
A-Emotion: stars
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I haven't seen him for three years. ok
He hasn't smoked for two weeks. ok
When did he arrive? ok
He arrived at 2.00. ok
Did you lock the door before you left the house? ok
I have read his books when I was at school.
I enjoyed them very much. ok
I have never drunk whisky. ok
I have written the letter but I can't find a stamp. ok
I just cleaned them. ok
I left home at 8:00 and got here at twelve. ok
I have done did this sort of work when I was an apprentice.
He has just gone went out.
He went out ten minutes ago. ok
Did you have breakfast yet? okYes, I had it at 8:00. ok
I met him last June. ok
Did you see the moon last night? ok
The concert has began at 2:30 and lasted for two hours.
Everyone enjoyed it very much.

Please check if the tenses are correct. I don't know when to use Present perfect and when the simple past.