题目

Suzy won an award in the USA for her popular talk show on TV. Her show is very popular so even people all over the world know it. Why is her show so popular? Because she cares about people and the world. She usually invites important people to her show to talk about some important issues that everyone cares about. And she is not afraid to fight with the bad things. One of her famous stories is about the mad cow disease(疯牛病). When Suzy learned that some businessmen(商人) sold bad beef and lied to people that the cows were without mad cow disease, she got angry and worried. She d下列推断错误的个数是（ ）①命题“若，则”的逆否命题为“若，则”②命题“若，则”的否命题为：若“,则”③“”是“”的充分不必要条件④若为假命题，则，均为假命题A．1 B．2 C．3 D．4