B2 the period in the day when light from the sun begins to appear in the sky拂晓，破晓，黎明
C1 the start of a period of time or the beginning of something new…的开始；…的曙光
from early morning until night从早到晚
She slept fitfully throughout the night and arose before dawn.
Three prisoners were involved in a dawn jailbreak today.
They mounted a surprise attack at dawn.
She's always up before dawn.
They partied till dawn.
If a day or period of time dawns, it begins.破晓；开始
mainly UK to become known or obvious见分晓，水落石出；变得明朗