She let me go.

Explanation
Active Voice: Let + indirect object + first form of a verb + direct object. Passive Voice: Let + direct object + be + third form of a verb + by + indirect object.

Explanation
This sentence is an interrogative sentence and started with  has . The passive voice will be also started with  has . Formula: Has + subject + been + V 3  + Optional Agents.

Explanation
Active Voice: Paint the windows.   Passive Voice: Let the windows be painted. The sentence is in Imperative Mood and Simple Present Tense.  

Explanation
" Children cannot be expected to understand these problems. " Children cannot be expected to understand these problems. ( Passive ) The sentence is in Simple Present Tense. ( Active ) Modal ( can ) has been used. The other options are incorrect because they either misuse the word order or grammar.

Explanation
People believe that donkeys are the stupid creatures means لوگوں کا ماننا ہیکہ گدھے احمق مخلوق ہیں   It is believed that donkeys are the stupid creatures مانا جاتا ہیکہ گدھے احمق مخلوق ہیں OR Donkeys are believed to be the stupid creatures. Sometimes we have to skip "People" while converting the sentence into passive. Present Indefinite Tense Active Voice: Subject + Verb + Object Passive Voice: Object + is/am/are+ third form of a verb + by + subject.

Explanation
This is a sentence of Present Continuous Tense. Present Continuous Tense Active Voice: Subject + is/am/are + First of verb + ing + obect . Passive Voice: Object + is being/am being/ are being + third form of verb + by + subject.

Explanation
Which book did she like the most is an interrogative sentence of Past Indefinite Tense. Which means کونسا یا کونسی یا کس Book means کتاب Like the most بہت زیادہ پسند کرنا Which book did she like the most means وہ کس کتاب کو بہت زیادہ پسند کرتی تھی Past Indefinite tense Active Voice= Subject +  Second Form of Verb + Object. Passive Voice = Object + was/were + third of verb + by + subject.

Explanation
Active Voice: Look at the poll results-do they inspire hope? Passive Voice: Let the poll results be looked at is hope inspired by them? Is is the helping of present indefinite tense in passive voice.

Explanation
Active Voice: What one must do. Passive Voice: What must be done. Active Voice: One must do properly. Passive Voice: Must be done properly. Note:- Before and after comma, both sentences must be changed into passive voice

Explanation
When cream is separated from the milk,  the density of the milk increases. The pH range of fresh milk is  6.4 to 6.8.