Explanation

 He has eaten the pizza which he bought last night

 Correct. The sentence uses correct tense and article usage:

"has eaten" (present perfect) – recent action,

"which he bought last night" – past simple for a specific past time ("last night")

Explanation

  Passive voice is used here.

The correct past participle form is "spoken."

Explanation

The windows have been cleaned by the butcher.

The sentence is in present perfect tense: has cleaned.

In passive voice, it becomes: have been cleaned (for plural subject: the windows).

Explanation

The obstacle course was run by me in record time.

This is the passive voice of the active sentence "I ran the obstacle course in record time."

In passive voice: Object + was/were + past participle + by + subject

Explanation

The sentence is in present perfect tense ("have lost"), so the passive voice should be in the form: has/have been + past participle.

"Our basket of chocolates has been lost by us" correctly matches this structure.

Explanation

The original sentence is in simple past tense: "He published..."

The passive voice of a simple past sentence follows the structure: Object + was/were + past participle + by + subject

Therefore, "His second book was published by him..." is correct.

Explanation

Present continuous active voice ("are repairing") changes to "is being repaired" in passive voice.

The subject (they) becomes the agent in the passive sentence.

Explanation

The sentence is in simple present tense, so the passive voice follows the structure:

Object + is/are + past participle + by + subject

Hence, "Pets are kept by Elizabeth" is correct.

Explanation

In passive voice, the object of the active sentence becomes the subject.

"A song is not sung by him" is the correct passive construction for the present tense.

Explanation

In passive voice, the subject receives the action, rather than performing it.

The sentence "The student was praised by the teacher" follows this structure, where "the student" is the receiver of the action.