They not only finished the work on time _________ did it perfectly.

• Correct answer: They not only finished the work on time but also did it perfectly.

• Use of Not only .... But also:
- Not only যদি subject এর আগে বসে তাহলে But also-ও subject এর আগে বসে।
- আবার Not only যদি object এর আগে বসে তাহলে But also-ও object এর আগে বসে।

• Structure:
- Subject + verb + not only + noun/ adjective/ adverb + but also + noun/ adjective/ adverb. Or,
- Subject + not only + verb + but also + verb.

• Example sentence:
- He writes not only correctly but also neatly.
- Robert is not only talented but also handsome.
- Beth plays not only the guitar but also the violin.

Source: A Passage to the English Language, S.M. Zakir Hussain.