1
be under lockdown
under lockdown 表示处于禁闭状态，lockdown 在此为名词。
The prisoners were under lockdown after the riot.
暴乱之后，囚犯们处于一级防范禁闭状态。
一级防范禁闭
先理解核心含义，再看它在真实句子里的用法。
一级防范禁闭
the act of confining prisoners to their cells, usually to regain control during a riot
The prisoners were under lockdown after the riot.
暴乱之后，囚犯们处于一级防范禁闭状态。
封锁；禁闭(将人限制在室内或指定区域的安全措施,常用于疫情或动乱)
The confinement of people in their own rooms (e.g., in a school) or cells (in a prison), or to their own homes or areas (e.g., in the case of a city- or nation-wide issue) as a security measure after or amid a disturbance or as a non-pharmaceutical intervention in a pandemic.
During the riot, the warden ordered a lockdown of the entire cell block.
暴乱期间，监狱长下令对整个牢房区实行一级防范禁闭。
The prisoners were kept in their cells for three days after the lockdown was announced.
宣布一级防范禁闭后，囚犯们被关在牢房里三天。
Several prison lockdowns this year were triggered by fights among inmates.
今年监狱的几次一级防范禁闭都是由囚犯之间的斗殴引发的。
under lockdown 表示处于禁闭状态，lockdown 在此为名词。
The prisoners were under lockdown after the riot.
暴乱之后，囚犯们处于一级防范禁闭状态。
impose a lockdown 强调由当局下令实行禁闭。
The warden imposed a lockdown to regain control.
监狱长实施一级防范禁闭以重新控制局面。
解除禁闭常用 lift；lockdown 为可数名词，复数为 lockdowns。
They lifted the lockdown the next morning.
第二天早上他们解除了禁闭。
Not this
The prisoners were lockdown all day.
Use this
The prisoners were in lockdown all day.
lockdown 是名词，不是形容词，不能直接放在 be 动词后作表语；表示“处于一级防范禁闭状态”要用介词短语 in lockdown。
Not this
The warden ordered lockdown after the riot.
Use this
The warden ordered a lockdown after the riot.
lockdown 表示“一次（对囚犯的）一级防范禁闭”时是可数名词，单数形式前需要冠词；ordered lockdown 缺少冠词，应改为 ordered a lockdown。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
进入一级防范禁闭状态
The entire prison went into lockdown after the fight broke out.
斗殴发生后，整座监狱进入了一级防范禁闭状态。
实施一级防范禁闭
The warden decided to impose a lockdown to regain control.
典狱长决定实施一级防范禁闭以重新控制局面。
解除一级防范禁闭
The lockdown was lifted the next morning after order was restored.
秩序恢复后，第二天早上解除了禁闭。
在一级防范禁闭期间
Prisoners remained in their cells during the lockdown.
一级防范禁闭期间，囚犯们待在牢房里。
监狱一级防范禁闭
The prison lockdown lasted for two days.
这次监狱禁闭持续了两天。
Use lockdown naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
联想：lock（锁）+ down（往下），把囚犯锁回牢房、压下去，就是“一级防范禁闭”。
语域：formal 常见场景：prison administration、riot control、official announcements 此义项为正式/机构用语，多用于监狱管理、官方通报或新闻报道等正式场合；口语中较少出现。
此义项特指监狱将囚犯关入牢房以防骚乱，并非疫情封控。
Dictionary facts from ECDICT, WIKTIONARY.