They're all grammatical. The very last sentence is a bit awkward. The others are fine.
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alc24 1 What am I bid for this fine vase?
2 What tells you that she's serious about working here./ How do you know she's serious...
3 I found on your computer what i found on mine.
I Found what you found on your computer on mine.alc24but for some reason 1 sounds off, its seems to me that its missing a word?
What a