I sing a song改爲過去完成時 ,再改爲被過去完成時的被動語態,A song _____ by me

題目：

I sing a song改爲過去完成時 ,再改爲被過去完成時的被動語態,A song _____ by me

解答：

I had sung a song.
過去完成時的被動語態:A song 【 had been sung】by me.
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