box spring
noun/ˈbɒks sprɪŋ/
/ˈbɑːks sprɪŋ/
[usually plural]- each of a set of metal springs inside a box that is covered with cloth and used under a mattress as part of a bed
盒形弹簧：盒内的一组金属弹簧中的每一个都用布覆盖，并在床垫下用作床的一部分 - For a firm bed, place a board between the mattress and the box springs.
对于坚固的床，请在床垫和弹簧床之间放置一块板。
- For a firm bed, place a board between the mattress and the box springs.