She pulled out the plug and let the water drain away.

她拔起塞子放掉了水。

The water will soon drain away.

水很快就会流尽。

The water will soon drain away [off].

水很快就会流掉。

Cherish life, and never let it drain away.

珍惜生命，莫让它白白流失。

Hope and energy drain away over the years.

岁月逐渐使精力和希望枯竭了。