他黎明时分就起床。

He gets up at ___the ___crack ___of ___dawn.

从黎明时分到睡觉时间，市民们不得不呼吸从汽车、自行车或工厂排放出的各种气体。

From ___the ___crack ___of ___dawn until bedtime, citizens have to breathe various gases emitted from cars, bikes, or factories.

探险队在黎明时分出发，以避开午间的炎热。

The expedition set off at ___the ___crack ___of ___dawn to avoid the midday heat.