"Loose" is not a verb, it is an adjective, there there is no tense for it.
The past perfect tense of "loose" is "had lost". For example: "She had lost her keys before arriving at the party."
The past tense of "exist" is "existed." The past perfect tense is "had existed."
The past tense of "bleed" is "bled." The past perfect tense of "bleed" is "had bled."
The past tense of sit is sat. The past perfect tense of sit is had sat.
The past perfect tense of "submit" is "had submitted."
The past perfect tense of "confront" is "had confronted."
The past tense of "exist" is "existed." The past perfect tense is "had existed."
The past perfect tense of hope is had hoped.
The past tense of "bleed" is "bled." The past perfect tense of "bleed" is "had bled."
The past tense of sit is sat. The past perfect tense of sit is had sat.
present tense past tense future tense present perfect tense past perfect tense future perfect tense present progressive tense past progressive tense future progressive tense present perfect progressive tense past perfect progressive tense future perfect progressive tense
Perfected is the past tense of perfect.
"Had been" is the past perfect tense of be.
The past perfect tense of 'get' is 'had gotten'
The past perfect tense of "do" is "had done." For example, "She had done her homework before dinner."
The past perfect tense of borrow is "had borrowed."
The past perfect tense of "think" is "had thought."
The past tense of paint is painted. Had painted is the past perfect tense.