许多登山者梦想征服世界第二高峰K2。

Many climbers dream of conquering ___K2, the world's second highest mountain.

土壤测试显示缺乏钾元素，建议添加含K2的肥料。

Soil tests indicate a potassium deficiency, so adding fertilizer with ___K2 is recommended.

这款手机真的是顶级中的顶级，性能简直无可挑剔。

This phone is truly ___K2—the performance is flawless.