The gemara at the end of 9b asks that according to rava who learns from the passuk of Ki Yikach Ish Ishah u'Ba'alah that kiddushin only works if you can do Bi'ah afterwards, but if u can't do Bi'ah afterwards then kiddushin doesn't work, so asks the Gemara (according to Rashi) that how will he learn both Derashos of rebbi before that number 1 Bi'ah works as kiddushin and number 2 that it's coming to exclude a case of Amah that over there Bi'ah doesn't work.
So I don't understand why the gemara has got shver both of these drashos of how to learn that Bi'ah works and how we can exclude ??? that Bi'ah doesn't work. because why can't u say like rebbi said before that the way we know that Bi'ah works is from the fact that it wrote u'Ba'alah and not u'Ba'al (like the gemara said a couple of lines before) and therefore the whole question of the gemara should be on Amah that since now we use this word of u'Ba'alah to teach us that it has to be a kiddushin which is handed over for Bi'ah so now I have no Mekor to tell us that it's coming to exclude a case of Amah. (But at the end of the day I still have a mekor that Bi'ah works, from the fact that we could have written u'Ba'al?)
Benzi, London
1) The way that Rebbi knows that Bi'ah works is not from the fact that it wrote "u'Ba'alah" and not "u'Ba'al"; it is from the fact that the Torah wrote "u'Ba'al," as Rashi writes.
2) Benzi, your question is the question of the Gemara -- that since Rava learns from "u'Ba'alah" that "Kidushin she'Ein Mesurin l'Bi'ah Lo Havu Kidushin," how does Rava know that Amah cannot be acquired by Bi'ah? The Gemara answers that since it did not say "O Ba'alah" but rather it said "u'Ba'alah," this means that we can learn everything from here; including the Din that Bi'ah does not work for Amah.
Kol Tuv,
Dovid Bloom
So if the whole question of the gemara is that how do we know the mekor that by amah you can't be koneh her with biah, then why does Rashi (at the end of ?"? ????? ???? DH u'l'Rava D'Amar)write that the question of the gemara is that how do we know BOTH the drasha of rebbi and also to be ???? ??? but according to what you were saying the question of the Gemara should be only that how do we know amah you can't be koneh with biah?
Rashi means to say that now, according to Rava, there are actually 3 things that we have to derive:
(a) "Kidushin she'Ein Mesurin l'Bi'ah Lo Havu Kidushin."
(b) Kidushin can work through Bi'ah.
(c) Bi'ah does not work for Amah.
Rashi writes that the question of the Gemara now is that since one of the Derashos has been used up to teach (a), from where do we have two Derashos left to teach (b) and (c)?
Kol Tuv,
Dovid Bloom