The sky darkled at the approaching storm.

风暴来临前天空渐渐暗了下来。

The night darkles rapidly.

夜很快地黑暗下来。

The precipice darkles in front.

山崖的前面是阴暗的。

If the silvered jewelry do not keep in a sealed environment or wipe it oftenly, it will caused the the color and luster become darkle.

银饰若未密封保存或经常擦拭，易使色泽变暗。