作者在给“百千万骨干教师”讲授逻辑问题时 ,一位教师向我提出了一个令他困惑不解的问题 ,下面是解决此问题的全过程 .(为叙述方便 ,把“百千万骨干教师”视为学生 )问题 :原命题　若 x≥ 0 ,则 x2 ≥ 0 .逆否命题　若 x2 0 ,则 x0 .学生甲 :逆否命题这样写对吗 ?教师 :对呀 When the author taught logical questions to the “one hundred million backbone teachers,” one teacher asked me a question that puzzled him. The following is the entire process to solve this problem. The backbone teacher is regarded as a student. Question: If the original proposition is x ≥ 0, then x2 ≥ 0. If the inverse proposition is x2 0, then x0. Student A: The inverse proposition is written correctly? Teacher: Right