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in one's pajamas
in one's pajamas 强调“穿着睡衣”的状态，常作方式状语。
She answered the door in her pajamas.
她穿着睡衣去开门了。
宽松束带长裤
先理解核心含义，再看它在真实句子里的用法。
宽松束带长裤
loose trousers with a drawstring waist, worn by men and women in some Asian countries
She answered the door in her pajamas.
她穿着睡衣去开门了。
此义指亚洲部分地区穿的束带宽松裤，并非睡衣。
Clothes for wearing to bed and sleeping in, usually consisting of a loose-fitting shirt and pants/trousers.
Loose-fitting trousers worn by both sexes in various southern Asian countries including India.
At the village market, many farmers wear loose cotton pajamas and long shirts.
在乡村集市，许多农民穿着宽松棉长裤和长上衣。
The tailor made a pair of white pajamas with a drawstring waist for the wedding.
裁缝为婚礼做了一条带抽绳腰带的白色宽松裤。
The dancers wore black pajamas and bright sashes as part of their traditional costume.
作为传统服饰的一部分，舞者们穿着黑色宽松裤，系着鲜艳的腰带。
in one's pajamas 强调“穿着睡衣”的状态，常作方式状语。
She answered the door in her pajamas.
她穿着睡衣去开门了。
pajamas 是复数名词，与 a pair of 搭配表示一条睡裤。
I bought a new pair of pajamas.
我买了一条新睡裤。
put on 强调穿上这个动作。
He put on his pajamas and went downstairs.
他穿上睡衣下楼去了。
change into 指换穿另一种衣物。
She changed into her pajamas as soon as she got home.
她一回到家就换上了睡衣。
Not this
I wore pajama to bed.
Use this
I wore pajamas to bed.
pajamas 是复数名词，即使指一套也始终用复数形式，不能去掉 s 变成单数形式。
Not this
She wore pajamas pants to bed.
Use this
She wore pajama pants to bed.
pajama 作定语修饰名词时用单数形式（如 pajama pants），不用复数形式 pajamas；这不同于作主语或宾语时的复数用法。
Not this
My pajamas is too small.
Use this
My pajamas are too small.
pajamas 是复数名词，作主语时谓语动词要用复数 are，不能用 is；这是主谓一致规则。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
一套睡衣
I need to buy a new pair of pajamas.
我需要买一套新睡衣。
穿着睡衣
Don't go to the door in your pajamas.
别穿着睡衣去开门。
穿上睡衣
It's time to put on your pajamas and go to bed.
该穿上睡衣上床睡觉了。
法兰绒睡衣
He wears flannel pajamas in the winter.
他冬天穿法兰绒睡衣。
换上睡衣
She changed into her pajamas after work.
她下班后换上了睡衣。
舒适的睡衣
These cozy pajamas keep me warm at night.
这套舒适的睡衣让我夜里保持温暖。
了不起的人或事物；极好的东西
He thinks his new headphones are the cat's pajamas.
他觉得他的新耳机棒极了。
Use pajamas naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
pajamas=睡衣：首音pa像‘趴’，睡前趴一下，穿上它舒服入眠。
语域：neutral 常见场景：服装描述、日常对话 该义项指腰间系带的宽松长裤，多用于服装款式描述的场合，日常对话中也较常见；不过 pajamas 在美式英语中通常更常指睡衣，需结合上下文判断。
通常以复数形式出现；表示“一条/一套”时可说 a pair of pajamas。
Dictionary facts from ECDICT, WIKTIONARY.