山区在冬季经常会有降水。

Mountainous areas often experience ___precipitation during winter.

在实验中，我们观察到溶液中的铜离子逐渐沉淀。

During the experiment, we observed the ___precipitation of copper ions from the solution.

她因行事冲动而多次陷入困境。

Her ___impulsiveness in action has gotten her into trouble many times.