Past Future Perfect Continuous Tense

Formula :

(+) : S + would + have + been + Ving

(-) : S + would + not + have + been + Ving

(?) : Would + S + have + been + Ving

Example :

 (+) Mrs. Anisa Munif would have been walking here for seventeen years

 (-) Mrs. Anisa Munif wouldn’t have been walking here for seventeen year

 (?) Would Mrs. Anisa Munif have been walking here for seventeen years?