1). Been sit2). Being sat3). Been sat4). Been sitting

1.	1). Been sit2). Being sat3). Been sat4). Been sitting
Answer» The verb before the blank is the auxiliary PAST tense verb 'had'. So the tense of the sentence either becomes past perfect, which exists in the form of had + past participle form of the verb or past perfect continuous, for which the RULE is had + been + verb in continuous form (-ing). Option 4 SHOWS past perfect continuous tense, so it MUST be CORRECT. Therefore, the correct answer is option 4.

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