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be externally + adj./past participle
externally 修饰形容词或过去分词，表示状态或动作来自外部。
The equipment is externally powered.
这台设备由外部供电。
在外部；从外面；外表上
先理解核心含义，再看它在真实句子里的用法。
在外部；从外面；外表上
on or from the outside
The equipment is externally powered.
这台设备由外部供电。
在外部；在外表上。
on the surface or the outside
The building is inspected externally every year.
这座建筑每年都从外部进行检查。
This medicine is applied externally, not taken by mouth.
这种药只能外用，不能口服。
The organization was criticized externally for its poor decisions.
该组织因决策不当而受到外界的批评。
externally 修饰形容词或过去分词，表示状态或动作来自外部。
The equipment is externally powered.
这台设备由外部供电。
多用于药品或化妆品，表示涂在皮肤表面，而非口服。
Apply the cream externally.
将这药膏外敷。
句首作评注性状语，表示“就外表而言”。
Externally, the machine looks old.
从外表看，这台机器很旧。
Not this
The equipment should be cleaned external.
Use this
The equipment should be cleaned externally.
这里需要副词来修饰动词 cleaned，不能用形容词 external。中文学习者常因“外部地”在中文里没有词形变化而误用形容词，但英语中修饰动词必须用副词 externally。
Not this
The engine is externally to the cabin.
Use this
The engine is external to the cabin.
be 动词后应接形容词短语 external to 来表示“在……外部”，而不是副词 externally。副词一般不能作表语，所以去掉 -ly 改用形容词 external。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
外部可见的
The cracks were externally visible, but the damage inside was worse.
裂缝在外部可见，但内部的损坏更严重。
由外部资助的
The research project was externally funded by a private foundation.
这个研究项目由一家私人基金会外部资助。
外部强加的
The villagers resisted the externally imposed rules.
村民们抵制了外部强加的规则。
由外部管理的
The company's IT services are externally managed.
该公司的IT服务由外部管理。
面向外部的
She works in an externally facing role, dealing with clients directly.
她担任面向外部的职务，直接与客户打交道。
经外部审计的
The financial statements are externally audited every year.
财务报表每年都经过外部审计。
Use externally naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
external 以 exit 的 ex 开头，出口在外面；副词后缀 -ly 表方式，所以是「从外部/在外面」。想象从门外往里看，就是 externally。
语域：mixed 常见场景：技术/医学描述、书面说明、外观比较 该词属于较正式用语，通常用于书面或专业语境（如技术、医学、外观比较），日常口语中更常说 outside 或 on the outside；在一般描述中也可使用。
internally、eternally、maternally、paternally、fraternally 与 externally 押韵（重读元音 /ɜːr/ 及之后 /nəli/ 相同）。naturally 拼写也以 -ally 结尾，但重音在首音节 /ˈnæ/，发音 /ˈnætʃərəli/，并不押韵，请注意区分。
Dictionary facts from ECDICT, WIKTIONARY.