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Help Inspector Clouseau eliminate impossible theories about the locked-room mystery. Select ALL the options that correctly complete the sentence to express that escaping through the window was impossible.
The window was painted shut from the inside, so the thief ____________ through it!
The correct answers are couldn't have escaped and can't have escaped.
To deduce that something was impossible in the past, standard English uses can't have or couldn't have + past participle.
"Mustn't have" is generally avoided for logical impossibility in standard grammar (we prefer can't/couldn't have). "Had not to escape" is grammatically incorrect.