我们徒步跋涉穿越了整片沙漠。

We ___trekked across the entire desert on foot.

为期两周的徒步旅行穿越喜马拉雅山脉是一次艰难的长途跋涉。

The two-week ___trek through the Himalayas was a challenging long journey.

我们背着沉重的背包，艰难地徒步穿越了山区。

With heavy backpacks, we ___trekked through the mountainous area with difficulty.