She plucked some flowers. (passive)

Past Indefinite tense কে passive করতে হলে -Active voice এর object +was/were+v এর(past participle)+by+subject এর object.- সুতরাং Some flowers were plucked by her. সঠিক ।
-Some flowers are plucked by her.বাক্যটি Past Indefinite এ থাকায় auxiliary verb are এর স্থলে were বসবে ।
- Some flowers had been plucked by her. past indefinite tense এর voice past perfect করা হয়েছে যা সঠিক নয় ।
- She was plucked some flowers. এই বাক্যে subject She কে object করা হয় তাই এটি ভুল ।

Source: Applied English Grammar and Composition by P. C. Das