机器内部复杂的齿轮系统令人印象深刻。

The machine's intricate ___gears are impressive.

别忘了带上你的滑雪装备，我们明天一早就出发。

Don't forget to bring your ski ___gear, we're leaving early tomorrow.

当车速增加时，你需要换到更高的档位。

You need to shift to a higher ___gear as the car speeds up.