<1. 歌手 & 背景介绍>
Katy Perry (凯蒂·派瑞) 1984年10月25日出生于加州圣巴巴拉的一个基督徒家庭，美国新晋超人气歌手。Katy Perry一曲《I Kissed a Girl》唱遍了大街小巷。凯蒂·佩里自出道以来就一直话题不断，个人首张专辑里将《Ur so Gay》和《I Kissed a Girl》两首带有强烈暗指寓意的歌曲作为主打。Katy Perry在漂亮的身躯下，迅速成为今夏美国流行音乐新标杆。单曲《I Kissed a Girl》取得美国单曲榜七连冠之后，又霸占英国单曲榜四周。连流行指标麦当娜 (Madonna) 也"臣服"于她，成为她的头号粉丝。成功《滚石》杂志还为她这首备受争议的热门单曲采访了她。麦当娜也称赞 Katy Perry是"一位极具潜力的歌手"。

 <2. 歌词>

You change your mind (1)
Like a girl changes clothes
Yeah you, PMS (2)
Like a b***
I would know
And you over think (3)
Always speak
Cryptically (4)
I should know
That you're no good for me

Cause you're hot then you're cold
You're yes then you're no
You're in then you're out
You're up then you're down
You're wrong when it's right
It's black and it's white
We fight, we break up
We kiss, we make up (5)
You don't really want to stay, no
But you don't really want to go-o
You're hot then you're cold
You're yes then you're no
You're in and you're out
You're up and you're down

We used to be
Just like twins
So in sync
The same energy
Now's a dead battery (6)
Used to laugh about nothing
Now you’re plain boring (7)
I should know that
You're not gonna change

Cause you're hot then you're cold
You're yes then you're no
You're in then you're out
You're up then you're down
You're wrong when it's right
It's black and it's white
We fight, we break up
We kiss, we make up
You don't really want to stay, no
But you don't really want to go-o
You're hot then you're cold
You're yes then you're no
You're in and you're out
You're up and you're down

Someone call the doctor
Got a case of a love bipolar
Stuck on a roller coaster
Can't get off this ride (8)

You change your mind
Like a girl changes clothes
Cause you're hot then you're cold
You're yes then you're no
You're in then you're out
You're up then you're down
You're wrong when it's right
It's black and it's white
We fight, we break up
We kiss, we make up (X2)
(You) You don't really want to stay, no
(but you) But you don't really want to go-o
You're hot then you're cold
You're yes then you're no
You're in and you're out
You're up and you're down

 <3. 注释>

(1) Change your mind 改变主意
I was afraid that Liz would change her mind and take me back home.

(2) PMS (= premenstrual syndrome) 
经前身体和情绪方面不舒服的症状

(3) Over think 想太多
（“over”搭配动词表示“过度”）
Overpopulation
Overcooked vegetables
Overweight

(4) Cryptically 模糊地（副词）
Cryptic 神秘的；意思含糊的（形容词）
Cryptic remark/comment/statement

(5) Fight 吵架；争吵（动词）

Fight with 
I heard her fighting with the boss.
Fight about/over 
They're fighting about who should do the dishes.

Break up 分手；分别；分离
The couple broke up last year.
Has Sam really broken up with Lucy?

Make up (with) 重修旧好；和好
Have you made up with Patty yet?

(6) We used to be just like twins, so in sync. The same energy now's a dead battery
以前我们像双胞胎一样形影不离，如此合拍。可是现在两个人之间好像没了电的电池。

Sync 同步；合拍（名词）
In sync (with something/somebody)
Be/move/work in sync 
The soundtrack is not quite in sync with the picture.

(7) Now you're plain boring 现在（觉得）你很无趣

Plain 十足的（在句子中起强调作用）
His motive was plain greed.
When you told him his house was too cold that was just plain bad manners.

(8) Got a case of a love bipolar. Stuck on a roller coaster. Can't get off this ride.
这里有个爱情两极化病例，好像坐过山车在半路卡住一样，动不了，又下不来。

Bipolar (情感)两极化（躁狂和抑郁状态交替）

Stuck 卡住的（形容词）
Sara tried to open the window but it was stuck.
They got stuck in a traffic jam.

Roller coaster 过山车