The past perfect tense is 'I had written'.The present perfect tense is 'I/you/we/they have written. He/she/it has written.
"Had written" is the past perfect tense of "write".
Wrote is the simple past; had written is the past perfect.
The present perfect tense is:I/You/We/They have written.He/She/It has written.The past perfect tense is:Had written.The future perfect tense is:Will have written.
Yes, it is a verb. It is the past tense of "to have" and used as an auxiliary verb in the past perfect tense.
The past tense of "exist" is "existed." The past perfect tense is "had existed."
The past tense of sit is sat. The past perfect tense of sit is had sat.
The past tense of "bleed" is "bled." The past perfect tense of "bleed" is "had bled."
The past perfect tense is had set.
The past perfect tense is had rung.
The past perfect tense is had bathed.
The past perfect tense of "confront" is "had confronted."
The past perfect tense of "learn" is "had learned."
The past perfect tense is had burned.
The past perfect tense of "submit" is "had submitted."
The past perfect tense of hope is had hoped.
The past perfect tense of "chose" is "had chosen."