It is "had sung".
The past perfect tense of "sing" is "had sung."
The present perfect tense with the past participle of "sing" is "have sung."
Sang is the past tense of sing. The present perfect tense of sing is I/We/You/They had sung; He/She/It has sung.
I sang I have sung is the present perfect tense. You would not say, "I sung the song well."
sang, not sung. "I sang a song" is correct, but "I sung a song" is not. You would say "I have sung a song", which is present perfect tense.
The past tense of "sing" would be "sang" or "sung".
The past perfect tense is had sung.
The present perfect tense with the past participle of "sing" is "have sung."
Sang is the past tense of sing. The present perfect tense of sing is I/We/You/They had sung; He/She/It has sung.
I sang I have sung is the present perfect tense. You would not say, "I sung the song well."
sang, not sung. "I sang a song" is correct, but "I sung a song" is not. You would say "I have sung a song", which is present perfect tense.
Present Continuous: They are singing.Past Continuous: They were singing.Unless you want the past tense of the word "sing," in which case:Simple Past: They sang.Past Perfect: They had sung.
The past tense of "sing" would be "sang" or "sung".
The future perfect tense of sing is "will have sung."
Existed is the past tense. 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 perfect tense of hope is had hoped.
The past perfect tense of "submit" is "had submitted."