"Has been singing" is in the present perfect progressive tense. "Is singing" is the present progressive tense.
Present tense - singing Past participle - sung
Subject + had + been + present participle For example, I had been singing.
Let's look at the verb 'sing'. Past tense - sang Past participle - sung Present tense - sing/sings Present participle - singing Future tense - will sing
'Ought to be' is present tense. 'Ought to have been' is past tense.
Past tense
Past tense.
Am is the present tense, first person singular conjugation of be. The past tense is was, and the past participle is been.
Be is present tense, Being is present progressing tense, and been is past tense
Have been is present tense and had been is past tense.
The present tense is sing and sings.The past tense is sang.The future tense is will sing.The present participle is singing and the past participle is sung.
Have is present tense. The past tense is had.
"Has been" is actually the present perfect tense.