弟弟很认真学习

younger brother studies very hard

→ 弟弟
phrase Rare #27,906
younger brother studies very hard 弟弟 refers to the speaker’s or another person’s younger brother, depending on context.
CH: 弟弟很认真学习,所以成绩很好。
EN: My younger brother studies very hard, so his grades are good.

他的弟弟很认真学习。

His younger brother studies very diligently.

她弟弟很认真学习。

Her younger brother studies very diligently.

她的弟弟很认真学习。

Her younger brother studies very diligently.

他弟弟很认真学习。

His younger brother takes his studies very seriously.