3 sentences for 循环 (xún​huán — circulate)

1. 血液在体内不断地循环。

   xuè​yè zài tǐ nèi bù​duàn de xún​huán.

   Blood circulates continuously in the body.

   Source: Dong Chinese Dictionary

2. 水都是在封闭的系统里循环的。

   shuǐ dōu shì zài fēng​bì de xì​tǒng lǐ xún​huán de.

   Water circulates in a closed system.

   Source: OpenSubtitles

3. 由于血液循环不畅，他的手臂感到有些麻痹。

   yóu​yú xuè​yè xún​huán bù chàng, tā de shǒu​bì gǎn​dào yǒu​xiē má bì.

   Due to poor blood circulation, his arm feels a bit numb.

   Source: Dong Chinese Dictionary