✅ Option A correctly converts the active sentence to the passive voice.

The object of the active sentence ("the iconic skyscraper") becomes the subject of the passive sentence, and the simple past tense ("designed") is correctly transformed into "was designed" (be verb in past tense + past participle).

The original subject ("the renowned architect") is introduced with "by", maintaining the original meaning and tense.

❌ Option B uses the present simple passive ("is designed") instead of the past simple passive, changing the original tense of the sentence.

❌ Option C remains in an active voice structure and changes the tense to past perfect ("had designed"), altering the original meaning.

❌ Option D fundamentally changes the meaning and the subject/object roles, implying the skyscraper was the one doing the designing.

✅ The original active sentence "The manager will approve..." is in the future simple tense. The correct passive form for the future simple is "will be" followed by the past participle of the main verb ("approved").

❌ Option A, "is approved," uses the present simple passive, which does not match the future tense of the original sentence.

❌ Option B, "was approved," uses the past simple passive, which is incorrect for an action that will happen "soon."

❌ Option D, "has been approved," uses the present perfect passive, which implies an action completed by now or in the recent past, not an action scheduled for the future ("soon").

✅ The active sentence "The students are studying English" is in the present continuous tense.

To convert a present continuous active sentence to passive, the structure is: object + is/am/are + being + past participle + (by agent).

Therefore, "English is being studied by the students" correctly follows this structure.

❌ "English was studied by the students" uses the past simple passive form.

❌ "English has been studied by the students" uses the present perfect passive form.

❌ "English is studied by the students" uses the present simple passive form.

✅ The active sentence "The students are completing their assignments" is in the present continuous tense (subject + is/am/are + verb-ing + object).

To convert a present continuous active sentence to passive, the structure is: object + is/am/are + being + past participle + (by agent).

Therefore, "Their assignments are being completed by the students" is the correct passive form.

❌ Option A "Their assignments were completed by the students" is in the past simple passive form.

❌ Option B "Their assignments have been completed by the students" is in the present perfect passive form.

❌ Option C "Their assignments are completed by the students" is in the present simple passive form.