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perhaps; possibly; maybe; by any chance; if I'm not mistaken
if; in case; in the event that
もしかしてあの人は以前の同僚ではないだろうか?
Could that person perhaps be a former colleague?
もしかして電車を乗り間違えたのではないか?
Could it be that I got on the wrong train?
もしかして遅刻するの?
Are you going to be late?