I woke up just before dawn.

我正好在拂晓前醒来。

I aim to be at the lake before dawn, so let's get moving.

我打算天亮之前到湖边，所以我们马上就动身吧。

A group of 80 attackers launched an all-out assault just before dawn.

有80名攻击者的一个小队在黎明前发起了一次全面进攻。

Let's start out before dawn.

让我们在天亮前起身。

The division commander ordered that we start the attack before dawn.

师长令我们在拂晓前发起攻击。