问答题
(∀x)P(x)∨¬(∃x)Q(x),求前束范式
问答题 (x)P(x)∧(x)Q(x),求前束范式
问答题 (x)(A(x)B(x))=>(x)A(x)(x)B(x)
问答题 (x)(A(x)→B(x))=>(x)A(x)→(x)B(x)