Answer:
Beautiful poems are written by my sister.
Step-by-step explanation:
The sentence is in the Simple Present tense. The 'Subject+is/am/are+V3+ by + O' structure is then used to change the Simple Present Tense into passive voice.
Active is S+V1/+s/-es + O.
O+is/am/are+v3+by+S = passive.
A questioning active will continue to be a questioning passive.