Dǎ lánqiú shí zuìhǎo dài shàng hùxī, bǎohù guānjié.
It's best to wear knee pads when playing basketball to protect your joints.
Lǎorén de xīgài bù hǎo, yīshēng jiànyì tā shǐyòng hùxī.
The elderly woman had bad knees, and the doctor recommended she use a knee brace.
