class 5 strong, third-person singular simple presentsitzt, past tensesaß, past participlegesessen, past subjunctivesäße, auxiliaryhabenorsein
The most frequent auxiliary with sitzen is haben: Ich habe gesessen. In northern and central Germany, only this form is used. In southern Germany, Austria, and Switzerland, sein is common in the vernacular and also, alternatively, in standard usage: Ich bin gesessen.
The most frequent auxiliary with sitzen is 
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