老板已经出差了。

Lǎobǎn yǐjīng chūchāi le.

The boss has already left on a business trip.

我每个月出差两次。

Wǒ měi gè yuè chūchāi liǎng cì.

I got on two business trips each month.

我下星期又要出差了。

Wǒ xià xīngqī yòu yào chūchāi le.

I'm going on a business trip again next week.