1 sentence for 间隙 (jiàn​xì — gap)

1. 下背部与地板之间应存在小的间隙。

   xià bèi​bù yǔ dì​bǎn zhī​jiān yīng cún​zài xiǎo de jiàn​xì.

   There should be a small gap between your lower back and the floor.

   Source: CCMatrix