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backrest of/on [furniture]
backrest 常与 of 或 on 连用，指明是椅子、沙发等家具的靠背。
The backrest of the chair is adjustable.
这把椅子的靠背是可调节的。
靠背
backrests — plural of backrest
先理解核心含义，再看它在真实句子里的用法。
靠背
a support that you can lean against while sitting
The backrest of the chair is adjustable.
这把椅子的靠背是可调节的。
椅背,椅子背部用于支撑坐者后背的部分。
The back piece of a chair, used to support the sitter's back.
车床滑动刀架上的导向装置,与工件接触以在车削时稳定工件。
A guide attached to the slide rest of a lathe, and placed in contact with the work to steady it in turning.
This chair's backrest is too low for me.
这把椅子的靠背对我来说太低了。
She adjusted the backrest of her car seat before the long drive.
长途开车前，她调整了汽车座椅的靠背。
The bus seats have high backrests to support passengers on bumpy roads.
公交车的座椅有高高的靠背，以便在颠簸的路上支撑乘客。
backrest 常与 of 或 on 连用，指明是椅子、沙发等家具的靠背。
The backrest of the chair is adjustable.
这把椅子的靠背是可调节的。
表示“靠在靠背上”时，动词常用 lean against。
She leaned against the backrest and closed her eyes.
她靠在靠背上，闭上了眼睛。
用 with a backrest 或 without a backrest 描述家具是否有靠背。注意复数形式为 backrests。
This bench has no backrest, so it is uncomfortable for long sitting.
这条长凳没有靠背，久坐不舒服。
Not this
I need backrest for my new chair.
Use this
I need a backrest for my new chair.
backrest 是可数名词，单数形式前需加冠词 a；中文没有冠词，所以学习者容易漏掉 a。
Not this
There is two backrests on this bench.
Use this
There are two backrests on this bench.
在 There be 句型中，be 的单复数由后面的名词决定；backrests 是复数，所以用 are 而不是 is。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
可调节靠背
This office chair has an adjustable backrest.
这款办公椅有可调节靠背。
靠背角度
You can change the backrest angle to suit your posture.
你可以调整靠背角度来适应你的姿势。
靠在靠背上
He leaned against the backrest and closed his eyes.
他靠在靠背上，闭上了眼睛。
椅子靠背
The chair backrest was broken.
椅子的靠背坏了。
Use backrests naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
把back（后背）和rest（休息）连起来：坐下时后背靠着它休息，就是靠背。
语域：neutral 常见场景：furniture、vehicle seating、office chairs backrest 是中性常用词，多用于描述椅子、汽车座椅等支撑背部的部件，在口语和书面说明中都算自然。它比 support 更具体，通常指座椅的靠背部分。
backrest 的重音在第一音节 /bæk/。back、black、pack、track 共享 /æk/ 的读音和拼写，但不是整词押韵。rest 和 crest 看起来像后缀 rest，但发音为 /rest/ 和 /krest/，元音是 /e/，与 /æ/ 不同，不押韵。
Dictionary facts from ECDICT, WIKTIONARY.