1
be watchful for sth
watchful for 后接可能出现的危险或迹象。
Parents should be watchful for signs of stress in their children.
父母应该警惕孩子身上的压力迹象。
警惕的；注意的；留神的
先理解核心含义，再看它在真实句子里的用法。
警惕的；注意的；留神的
vigilant; engaged in or accustomed to close observation
Parents should be watchful for signs of stress in their children.
父母应该警惕孩子身上的压力迹象。
完全敏锐、警惕或意识到的。
Fully observant, vigilant, or aware.
The security guard remained watchful all night, checking every car that entered the parking lot.
保安整晚保持警惕，检查每一辆进入停车场的车。
Parents should be watchful when their children are playing near the road.
孩子们在路边玩耍时，父母应该保持警惕。
Keep a watchful eye on your bag while you are at the station.
在车站时，要留神看好你的包。
watchful for 后接可能出现的危险或迹象。
Parents should be watchful for signs of stress in their children.
父母应该警惕孩子身上的压力迹象。
watchful of 表示对某人或某事保持关注或谨慎，比 watchful for 更侧重主动留意。
As a journalist, she is watchful of every detail in her article.
作为记者，她非常注意文章中的每一个细节。
keep a watchful eye on 是固定搭配，意为‘密切注视、留神’。
The lifeguards kept a watchful eye on the swimmers.
救生员密切注视着游泳的人。
Not this
She watchful of strangers.
Use this
She is watchful of strangers.
watchful 是形容词，不能单独作谓语；主语后必须有系动词 is（或 am/are）构成系表结构，所以加上 is 才正确。
Not this
He looked at me watchful.
Use this
He looked at me watchfully.
watchful 是形容词，不能修饰动词 looked；修饰动词应用副词 watchfully，所以此处要把 watchful 改为 watchfully。
Not this
Be watchful to pickpockets.
Use this
Be watchful of pickpockets.
watchful 表达“提防、警惕”时与介词 of 搭配，be watchful of 是固定搭配，不能用 to。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
密切注视；留神看护
Parents should keep a watchful eye on young children near water.
父母应密切注视在水边的小孩。
在…的严密注视下
The children played under the watchful eye of their parents.
孩子们在父母的严密注视下玩耍。
观察等待（暂不干预或治疗）
Instead of immediate surgery, the doctors chose watchful waiting.
医生们没有立即动手术，而是选择了观察等待。
提防；警觉地留意
Be watchful for any unusual symptoms after the trip.
旅途后要警觉地留意任何异常症状。
保持警惕
Police asked nearby residents to remain watchful.
警方要求附近居民保持警惕。
密切注视；留神看守
Parents should keep a watchful eye on their children when they are swimming.
孩子们游泳时，父母应密切留意他们的安全。
在某人的密切关注下
The children played in the park under the watchful eye of their teacher.
孩子们在老师的密切关注下在公园里玩耍。
观察等待；谨慎观望（指暂时不采取干预措施，密切观察情况的策略）
The doctor recommended watchful waiting rather than immediate surgery.
医生建议采取观察等待，而不是立即手术。
你们务要警醒，在真道上站立得稳，要作大丈夫，要刚强。
The security guard remained watchful throughout the night.
保安整夜保持警惕。
Use watchful naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
watch（注视）+ ful，像守夜人一直盯着看，警惕留心，也指醒着不睡的状态。
语域：neutral 常见场景：新闻报道、安全提醒、医疗观察、儿童看护 表示“警惕的、注意的”时，watchful 通常属于中性偏正式的用词，多用于书面或较正式场合，比如新闻报道、安全提醒、医疗观察等；日常口语中也可使用，但口语里更常说 alert。
这些 -ful 词只是拼写上的形近词，发音并不相同；没有常见词与 watchful /ˈwɒtʃfʊl/ 完全押韵。注意元音差别：如 careful /ˈkeə-/、helpful /ˈhelp-/、useful /ˈjuːs-/、wonderful /ˈwʌndə-/、beautiful /ˈbjuːtɪ-/、grateful /ˈɡreɪt-/ 均与 watchful 的 /ˈwɒtʃ-/ 不同。
Dictionary facts from ECDICT, WIKTIONARY.