1.文法二义性证明,证明下面文法有二义性文法1E->-EEE->-EE->aE->bE->c文法2P->PaP|PaP|cP|Pe|f2.最左推导,最右推导S->aB|bAA->aS|bAA|aB->bS|aBB|b给出句子aaabbabbba的最左和最右推导