The past perfect tense of enter is had entered.
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.
Existed is the past tense. The past perfect tense is had existed.
The past tense is bled, and the past perfect tense is had bled.
The past tense of sit is sat; the past perfect tense is had sat.
The past perfect tense of hope is had hoped.
The past perfect tense is had submitted.
The past perfect tense is had chosen.
The past perfect tense is "had confronted".
The past perfect tense is had set.
The past perfect tense is had burned.
The past perfect tense is had rung.
The past perfect tense of "learn" is "had learned."
The past perfect tense is had bathed.