Shaheen would never have taken the job if ____ what great demand it would make on his time.
he knew
he had been knowing
he had known
he was knowing
Explanation:
Correct Answer is: he had known
Conditional sentence এ যদি if যুক্ত অংশটি past perfect tense এ হয়, তাহলে অপর অংশটিতে would/could/might have বসে।