成长的烦恼25集里面最后杰生单独在房里唱得歌叫什么名字啊？

是唤回青春那集吧，《唤回青春》那集最后Jason弹吉他唱的那首：

《If I Fell》

If I fell in love with you
Would you promise to be true
And help me understand
'cause I've been in love before
And I found that love was more
Than just holding hands

If I give my heart to you
I must be sure
From the very start
That you would love me more than her

If I trust in you oh please
Don't run and hide
If I love you too oh please
Don't hurt my pride like her
'cause I couldn't stand the pain
And I would be sad if our new love was in vain

So I hope you see that I
Would love to love you
And that she will cry
When she learns we are two

If I fell in love with you