The past perfect tense of sleep is had slept.
The present perfect is -- have /has + past participle = has/have slept.
The past progressive tense of sleep is was/were sleeping.I was sleepingWe were sleepingYou were sleepingHe/She/It was sleepingThey were sleeping
Present perfect is formed with have / has + past participle. The past participle of sleep is slept, so the present perfect is have slept or has slept eg They have slept all day She has slept all day
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 is "had confronted".
The past perfect tense is had chosen.
The past perfect tense is had burned.
The past perfect tense is had set.
The past perfect tense is had rung.
The past perfect tense of hope is had hoped.