be online
系动词后作表语，表示设备已接入网络或系统处于运行状态。
The printer is online and ready to use.
打印机已联网，随时可以使用。
接入的；运行中的；本机可用的；单机可用的；进行中的；当前的；在常规线路上的；沿线的；系统:连接到更大网络(通常电气连接)
connected to the Internet or a computer network; accessible through the Internet
系统:连接到更大网络(通常电气连接)
Of a system: connected (generally electrically) to a larger network.
铁路、公交或航空系统的常规路线
on a regular route of a railroad or bus or airline system
可通过互联网获取或交付的
Available over, or delivered from, the Internet.
连接到计算机网络或可通过计算机访问
connected to a computer network or accessible by computer
连接到互联网的
Connected to the Internet.
正在进行中
being in progress now
在计算机系统上可用,即使未联网
Available on a computer system, even if not networked.
系统:活跃的,尤指建筑设施(如电力)或工厂、发电厂
Of a system: active, particularly building facilities (such as power) or a factory or power plant.
The online store offers free shipping on all orders.
这家网店对所有订单提供免费配送。
用法提示：此处 online 为形容词，修饰 store，表示“网上的、在线的”。
I prefer online classes because I can study at home.
我更喜欢在线课程，因为可以在家学习。
用法提示：此处 online 为形容词，修饰 classes，表示“通过互联网进行的”。
The system is online again after the maintenance.
维护之后，系统重新上线了。
用法提示：此处 online 为形容词，作表语，表示“联网的、在运行中的”。
系动词后作表语，表示设备已接入网络或系统处于运行状态。
The printer is online and ready to use.
打印机已联网，随时可以使用。
强调从离线转为联网的动作，常用于日常上网。
She goes online every evening to check her email.
她每天晚上都上网查看电子邮件。
作定语放在名词前，说明该事物通过网络提供或进行。
He bought an online course to improve his English.
他买了一门在线课程来提高英语。
多用于系统、设施或工厂开始运行、正式接入。
The new power plant will come online next year.
新发电厂将于明年投入运行。
grammar · medium
易错句子I online for two hours every night.
正确表达I go online for two hours every night.
online 是形容词（也可作副词），不能单独充当谓语动词。汉语“我上网”本身是动词短语，直译时容易把 online 当动词用；英语必须补出动词，构成 go online / get online / be online 这类搭配，所以要在 online 前加 go。
grammar · medium
易错句子I watched the concert in online.
正确表达I watched the concert online.
online 作副词时直接修饰前面的动词，本身已含“通过互联网”之意，不再加介词。汉语“在网上看”带有介词“在”，若照搬成 in/on online，介词就变成多余成分，句子不成立。
grammar · medium
易错句子My laptop has online, so I can work from home.
正确表达My laptop is online, so I can work from home.
online 是形容词，表示“处于联网状态”，须与 be 动词连用作表语。汉语“我的电脑有网”是动宾结构，直译成 have online 会把形容词误当名词使用，属于词性误用，应改为 is online。
网上购物
Online shopping has become part of everyday life.
网上购物已成为日常生活的一部分。
网上银行业务
She pays all her bills through online banking.
她通过网上银行支付所有账单。
在线课程
He signed up for an online course in programming.
他报名参加了一门编程在线课程。
在线支付
Online payment is fast and convenient.
在线支付既快捷又方便。
（发电厂、设备等）投入使用，开始运行
The new power plant will come online next year.
新发电厂将于明年投入使用。
Choose the next layer that will help you use online with more confidence.
Recommended next
Missing: Confusing words
Complete this area with confusing words.
Includes Context & register & Memory tip
Analyze the context and learn memory tricks to remember it.
More ways to explore
Includes Synonyms & Antonyms
Expand your vocabulary with synonyms and antonyms.
Includes Spelling & sound
Explore words with similar spelling endings or sounds.
Includes Word components & Thematic vocabulary
Learn how to build related words using roots, prefixes, and thematic clusters.
Includes Idioms & Cultural references
Discover idioms, slang, and famous pop culture quotes.
Dictionary facts from DICTIONARY_API_DEV, ECDICT, WIKTIONARY.
（设备）联机，连在网上
The printer is online, so you can print from any computer.
打印机已联机，你可以从任何一台电脑打印。