问答题每次火车都比某些汽车快。
问答题(z)(P(x)∧(x)R(x,z)→(y)Q(x,y))∨R(x,y)
问答题(x)(y)(R(x,y)∧Q(z))
问答题(x)(P(x)∧(x)Q(x))∨((x)R(x,y)∧Q(z))
问答题(x)(P(x)∧R(x))→((x)P(x)∧Q(x))