我和弟弟一起去学校。

Wǒ hé dìdi yìqǐ qù xuéxiào.

My younger brother and I go to school together.

弟弟比我小三岁。

Dìdi bǐ wǒ xiǎo sān suì.

My younger brother is three years younger than me.

弟弟喜欢跟我一起打篮球。

Dìdi xǐhuān gēn wǒ yìqǐ dǎ lánqiú.

My younger brother likes to play basketball with me.