If you don't, why should I?是什么意思?

Giving up, why should I we've come to far to forget
算了吧 我想尽办法要忘记
we're beautiful, we just got lost somewhere along the way
美丽的过去 其实我只要放弃自我就行了
so much was missing when you went away
你不在身边的时候 许多感觉都已经不在了
Let's start from here, lose the past
让我们重新开始 忘记过去
change our minds, we don't need a finish line
改变心意 我们不需要画地自限
let's take this chance not think too deep
让我们把握机会 不要再眷恋
of all those promises we couldn't seem to keep
那些我们 曾无法守住的诺言
I don't care where we go
我不在意 未来会带我们到哪里去
Let's start from here
让我们一起重新开始
standing here face to face a finger on your lips
面对面站在这 将手指贴在唇上
don't say a word don't make a sound silence surrounds us now
不作一声 就让沉默 现在包围我们
even when you were gone I felt you everywhere
这样 在你走之后 我仍然可以感受你在每个地方
Let's start from here, lose the past
让我们重新开始 忘记过去
change our minds, we don't need a finish line
改变心意 我们不需要画地自限
let's take this chance not think too deep
让我们把握机会 不要再眷恋
of all those promises we couldn't seem to keep
那些我们 曾无法守住的诺言
I don't care where we go
我不在意 未来会带我们到哪里去
Let's start from here
让我们一起重新开始
I've never been the one to open up
我从来都不是那个把爱说出口的人
but you've always been the voive within
但是 你永远是那个听见我心声的人
the only warmth from my cold heart
温暖我那颗已经冷却的心的人
Let's start from here, lose the past
让我们重新开始 忘记过去
change our minds, we don't need a finish line
改变心意 我们不需要画地自限
let's take this chance not think too deep
让我们把握机会 不要再眷恋
of all those promises
那些我们 曾无法守住的诺言
I don't care where we go
我不在意 未来会带我们到哪里去
Let's start from here
让我们一起重新开始
还有一个
为什么我要 放弃
我们经历了那么多 却从未忘记
我们的美丽 我们只是忘了
在途中某个地方
当你离开时,留下太多思念
合唱
让我们从这里开始,忘记过去
我们不需要要求到达终点
让我们乘此机会 不要想得太多
关于那些我们不能坚持的诺言
去哪儿无所谓
让我们从这里开始
让我们从这里开始
面对面站着
手指封上你的嘴唇
别说话 别出声
现在 宁静包围着我们
甚至在你离开后 我仍感觉你无所不在
合唱
我从不是个开放的人
但是你已是我冰冷的心中
仅存的一丝温暖.
让我们从这里开始,忘记过去
我们不需要要求到达终点
让我们乘此机会 不要想得太多
关于那些我们不能坚持的诺言
去哪儿无所谓
让我们从这里开始^

选B .
时态的测试,应该遵循如下原则:结合语境细心考虑,这句话的意思是“为什么我要后悔?我现在挣得没有（过去）那么多,但是我却更开心”.对比后面的enjoy也是用一般现在时来表示现在的状况.
其他时态都不符合语境.

Why should we learn English?
Today English become more and more important . And in China every student learns English and other people study English as well . But why should we learn English?
Firstly , English is one of offical languages . Secondly , we can read English books and talk to native speakers by learning English . Of course , if we speak English fluently we can travel all over the world . English is spoken in most countries. Thirdly or the most important one, learning English is ready for the exams. English is a main subject of all. The English exam has high scores.For the students,they will get low scores in all if they are weak in English. So, learning English is important,we should learn English well.