從Duolingo:

• 我的朋友在吃早飯。 – My friend is eating breakfast.
• 奶奶在跳舞。 – Grandma is dancing.
• 你在做作業嗎？ – Are you doing homework?
• 他們在學漢語。 – They are learning Chinese.(now, this week, these months, this semester, etc.)