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a thresher
thresher 作“打谷机”讲时为可数名词，复数形式是 threshers。
A thresher separates grain from the husks and straw.
打谷机把谷粒从谷壳和秸秆中分离出来。
打谷机；脱粒机
threshers — plural of thresher
先理解核心含义，再看它在真实句子里的用法。
打谷机；脱粒机
a farm machine for separating grain from husks and straw
A thresher separates grain from the husks and straw.
打谷机把谷粒从谷壳和秸秆中分离出来。
打谷者或打谷机；任何进行脱粒的人或物。
Anything or anyone that threshes.
一种现代的谷物脱粒农用机械,现为联合收割机的一部分,而非独立的机具。
A modern farm machine for threshing grain, now a part of combine harvesters rather than a separate implement.
The farmer uses a thresher to separate the wheat from the straw.
这位农民用打谷机把小麦从秸秆中分离出来。
The old thresher broke down in the middle of the harvest.
那台旧打谷机在收获季节中途坏了。
Modern threshers can separate grain from straw much faster than by hand.
现代打谷机分离谷粒和秸秆的速度比手工快得多。
thresher 作“打谷机”讲时为可数名词，复数形式是 threshers。
A thresher separates grain from the husks and straw.
打谷机把谷粒从谷壳和秸秆中分离出来。
the + thresher 可指长尾鲨这一类，注意与“打谷机”的含义区分。
The thresher is found in warm seas.
长尾鲨见于温暖海域。
Not this
The machine is used to thresher the grain.
Use this
The machine is used to thresh the grain.
thresher 是名词（打谷机/打谷者/长尾鲨），不是动词；表示“打谷、脱粒”的动词原形是 thresh。在 be used to 后接动词原形，所以要用 thresh。
Not this
These thresher are very efficient.
Use this
These threshers are very efficient.
thresher 是可数名词单数，复数为 threshers。句中 These 要求后面的名词用复数，所以必须加 -s。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
小麦脱粒机
The farmer bought a new wheat thresher before harvest.
农民在收割前买了一台新小麦脱粒机。
水稻脱粒机
This rice thresher can handle a large amount of paddy.
这台水稻脱粒机能处理大量稻谷。
长尾鲨
A thresher shark uses its long tail to herd and stun fish.
长尾鲨用它的长尾巴来驱赶和击晕鱼类。
远洋长尾鲨
The pelagic thresher is often spotted far from the coast.
远洋长尾鲨经常在远离海岸的地方被看到。
Use threshers naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
可以联想：长尾鲨甩尾如打谷机拍打谷穗，因此也叫 thresher；-er 表示打谷者/机。
语域：neutral 常见场景：农业、海洋生物学 该词通常作为中性词使用，多用于农业（打谷机）和海洋生物学（长尾鲨）语境；表示“打谷者”（人）较少见，多见于历史或文学描述。
与 thresher 真正押韵的有：fresher, pressure（pressure 拼写不同，但结尾读音同为 /ʃə/）。注意形近但发音不同的词：pleasure, measure, treasure（拼作 -sure 却发 /ʒə/）和 usher（拼作 -sher，但元音为 /ʌ/）。
Dictionary facts from ECDICT, WIKTIONARY.