光滑

它像婴儿的屁股一样光滑。

tā xiàng yīng ér de pì gu yī yàng guāng huá。

It's as smooth as a baby's bottom.

在光滑的路上开车会导致车祸。

zài guāng huá de lù shang kāi chē huì dǎo zhì chē huò。

Driving on a slippery road can lead to a car wreck.