An alarm clock.

注：alarm clock goes off意思是“鬧鐘響了”，同時go off也有“走開”的意思。

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The more you take, the more you leave behind. What is it?

What always ends everything?

I'm the part of the bird that's not in the sky. I can swim in the ocean and yet remain dry. What am I?

Which word in the English language becomes shorter when lengthened?