Háizi zài zhè tiáo hé lǐ yóuyǒng tài wéixiǎnle. This river is dangerous for children to swim in.
Yóuyǒng shǐ tuǐ bù qiángjiàn. Swimming makes your legs stronger.
Wǒmen jìnqíng zài hú lǐ yóuyǒng. We enjoyed swimming in the lake.
She taught me how to swim.
Wǒmen zài hú lǐ yóule yǒng. We swam by the lake.