有底[yǒu dǐ]
词典know how things stand and feel confident of handling them：有底；有根。
词典be fully prepared for what is coming：有底。
有底[yǒu dǐ]
know how things stand and feel confident of handling them; be fully prepared for what is coming:
例：他心里有底， 一点不慌。
He was not at all nervous, for he knew what to expect.