肄业
to attend (a school); to drop out (of college etc)
一夜爆红
to become popular overnight
一夜露水
one-night stand; ephemeral
一叶知秋
lit. the falling of one leaf heralds the coming of autumn (idiom); fig. a small sign can indicate a great trend; a straw in the wind
一叶障目
lit. eyes obscured by a single leaf (idiom); fig. not seeing the wider picture; can't see the wood for the trees
肄业证书
certificate of partial completion; certificate of attendance (for a student who did not graduate)