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decayed + noun
decayed 作定语，直接修饰名词。
The dentist filled a decayed tooth.
牙医补了一颗蛀牙。
腐烂的；腐朽的
先理解核心含义，再看它在真实句子里的用法。
腐烂的；腐朽的
Having undergone decay; rotted.
The dentist filled a decayed tooth.
牙医补了一颗蛀牙。
已腐烂的；腐朽的。
Having undergone decay, rotted.
The old wooden fence had decayed and was falling apart.
旧的木栅栏已经腐烂，正在散架。
The dentist removed the decayed tooth to prevent infection.
牙医拔掉了蛀牙以防止感染。
After years of neglect, the once vibrant neighborhood had become decayed and unsafe.
经过多年的忽视，曾经充满活力的社区变得破败且不安全。
decayed 作定语，直接修饰名词。
The dentist filled a decayed tooth.
牙医补了一颗蛀牙。
be decayed 表示处于腐烂的状态。
This wood is decayed and unsafe to build with.
这木头已经腐朽，不宜用来建造。
become decayed 强调从完好转为腐烂的变化过程。
Left in the rain, the cardboard became decayed within weeks.
纸板放在雨中，几周内就腐烂了。
Not this
I have decayed tooth.
Use this
I have a decayed tooth.
decayed tooth 表示“一颗蛀牙”，是可数名词短语，单数形式前必须加不定冠词 a/an；汉语没有冠词，所以学习者容易漏掉 a。
Not this
The dentist pulled out two decayed tooth.
Use this
The dentist pulled out two decayed teeth.
tooth 的复数是不规则形式 teeth，前面有 two 修饰时名词必须用复数，不能用单数 tooth。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
蛀牙；腐烂的牙齿
The dentist said my decayed teeth needed fillings.
牙医说我的蛀牙需要补。
腐朽的木头
The old shed was built from decayed wood and collapsed easily.
旧棚屋是用腐朽的木头建的，很容易就塌了。
腐烂的物质；腐殖质
The soil was rich in decayed matter from fallen leaves.
土壤富含落叶形成的腐烂物质。
腐烂的遗骸；腐烂的残骸
Archaeologists found the decayed remains of an ancient boat.
考古学家发现了一艘古船的腐烂残骸。
腐烂的叶子
A thick layer of decayed leaves covered the forest floor.
森林地面上覆盖着厚厚一层腐烂的叶子。
腐烂的肉；腐肉
The smell of decayed flesh filled the abandoned house.
废弃的房子里弥漫着腐肉的气味。
发长 /eɪ/ 音 (如 day, play)
Use decayed naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
联想牙医说“tooth decay（蛀牙）”，decayed 就是已经烂掉的状态，字母 -ed 表示“已经”，眼前浮现一颗蛀空的牙。
语域：formal 常见场景：dental/medical reports、scientific writing、literary description decayed 多用于正式或技术性语境，如牙科、生物学或文学描写；日常口语中更常说 rotten。
played, obeyed, afraid, and made all end with the /eɪd/ sound and rhyme with decayed. The same sound is spelled 'ay' in decayed and played, 'ey' in obeyed, 'ai' in afraid, and 'ade' in made. said looks similar to afraid (both contain 'aid') but is pronounced /sed/ and does not rhyme.
Dictionary facts from ECDICT, WIKTIONARY, WORDNET.