translate..how can i gain weightim a 15 years old teenager..and no matter how much i eat..my weight does not vary..why is that?

How can i translate this sentence?(In chinese)Sorry i can's speak chinese because i am american 'i blacked down.' anyone who can tell me how to translate it into chinese? translate..how can i gain weightim a 15 years old teenager..and no matter how much i eat..my weight does not vary..why is that? If you can translate this sentence ,I can have a how to translate this sentense?i hope you score. That's just how i see it .Translate how can i forget 'How long can I How can I go How can I How can I do how to translate the how to translate概率 who can translate 拉倒 Help!Who can tell me how to translate the 在途物资 into English word?Thanks!None! 为什么how can i=how to How much can i lose? how can i grow up?