(idiomatic) out of the blue, bolt from the blue, great surprise

to pour water (into); to dilute with water / (idiomatic) to hinder; to hamper; to throw cold water on; to put a damper on; to estrange (people)

(idiomatic) let the water carry it away, wipe the slate clean

water warmed in the sun

(formal) [I, we] wish you a happy new year (literally meet a good year)

excuse me; may I come in?

the student has surpassed his or her teacher

impermeable wall

(idiomatic) "a fish who's found water" → In one's element, a duck to water.

absorbing (knowledge) very quickly and naturally