dress up有三种常用的含义和用法：
1.装扮，打扮，盛装打扮；乔装打扮成……，装扮成;伪装成
She dressed up to impress her new boss.
她打扮得漂亮，以给她的新老板留下印象。
dress up in (clothing): 穿上特定的服装。
She dressed up in a stunning gown for the award ceremony.
她为颁奖典礼穿上了一件华丽的礼服。
She dressed up in a beautiful gown for the party.
她为派对穿上了一条漂亮的礼服。
She dressed up for her graduation ceremony.
她为毕业典礼打扮得漂亮。
We all dressed up for the wedding ceremony.
我们都盛装出席婚礼。
I will dress up in suits for the interview.
我会穿套装参加面试。
You do not need to dress up for dinner.
你们不必特意盛装赴宴。
You're all dressed up. Are you going somewhere?
你打扮得这么漂亮,要去哪？
I like to dress up for work every now and then.
我有时喜欢穿得整整齐齐地去上班。
Let's dress up and go out to the ball.
咱们穿戴整齐去参加舞会吧。
You don't need to dress up for this dinner.
这次去吃饭你不必穿上正式的衣服。
You don't have to get dressed up for this party.
你没必要为这次聚会而着盛装。
They dressed up for their anniversary dinner.
他们为纪念日晚餐穿得很漂亮。
We dressed up for the school ball on Christmas day.
我们为参加学校的圣诞舞会而盛装打扮。
The new recruits arrived early, all dressed up and raring to go.
新兵早早地就到了，都穿得整整齐齐，盼着出发。
Some people like to dress up in minks and diamonds.
有些人喜欢穿貂皮大衣，戴钻石首饰。
Should I dress up or dress down on the first date?
It depends.
第一次约会我应该穿得正式一些，还是休闲一些？
视情况而定。
dress up as/like（扮演成/像）
He dressed up as a pirate for Halloween.
他在万圣节时扮演成海盗。
The children dressed up in Halloween costumes for the party.
孩子们穿着万圣节服装参加聚会。
They dress up as ghosts and witches.
他们打扮成幽灵和巫婆的样子。
She was dressed up as a lady of high society.
她把自己打扮成一位贵妇人。
She dresses up as a fairy.
她盛装打扮成一个仙女。
Little girls dress up as angels for fiestas.
小女孩们在节日里扮成天使的样子。
She dressed up as an old woman.
她乔装打扮成一个老太太。
You could dress up as a fire man.
你可以装扮成一个消防员
He tried to organise things so that the trip would be dressed up as a UN mission.
他竭力筹备好各项事宜以便这次出行看上去像联合国代表团出访一样。
The band dressed up as the Beatles as a publicity stunt.
乐队扮作披头士乐队作为宣传噱头。
She dressed up as a witch for Halloween.
她在万圣节时扮成了女巫。
She dressed up as a princess for the school play.
她为了学校的戏剧表演扮成了公主。
打扮用英语可以说成dress up，或者是在口语中常用的fix up或spruce up也可以表示打扮的意思。
She dressed up for the party and looked stunning.
她打扮得漂漂亮亮地参加聚会。
He fixed himself up before going out on a date.
他在约会前把自己打扮好了。
I need to spruce up before the job interview.
面试前我需要打扮一下。
2.给……打扮，给……装扮
Mother loved to dress me up.
妈妈喜欢打扮我。
They dressed her up for the part of xi-er.
他们替她化装以扮演喜儿。
3. 修饰;美化;粉饰
dress up your room: 美化或装饰你的房间
She loves to dress up her room with colorful curtains and artwork.
她喜欢用彩色的窗帘和艺术品装饰她的房间。
They spent a lot of money dressing up the old building.
他们花费大量金钱来装饰这座旧建筑。
dress up a story: 为故事增色，使其更吸引人。
The author dressed up the story with vivid descriptions.
作者用生动的描述让故事更加引人入胜。
However you dress it up, a bank only exists to lend money.
无论你如何粉饰，银行就是为房贷而生的。
Politicians dress up their ruthless ambition as a pursuit of the public good.
政客们将他们的狼子野心美化成是谋求公共利益。