Usages of suì
他 今 年 二十 岁， 妹妹 比 他 小 两 岁。Tā jīnnián èrshí suì, mèimei bǐ tā xiǎo liǎng suì.
He is twenty years old this year; his younger sister is two years younger than him.
我 有 一 个 女 同学， 她 比 我 大 三 岁。Wǒ yǒu yì gè nǚ tóngxué, tā bǐ wǒ dà sān suì.
I have a female classmate who is three years older than me.
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