他是色盲，很难区分红色和绿色。

He's colorblind and can't ___distinguish between red and green easily.

有时很难区分西班牙语和葡萄牙语。

It's sometimes difficult to ___distinguish between Spanish and Portuguese.

区分商业关系和个人关系至关重要。

It is crucial to ___distinguish between business and personal relationships.