知乎，让每一次点击都充满意义 —— 欢迎来到知乎，发现问题背后的世界。 natural Such a perform represents a partial function on naturals, where the evidence of even (n) could possibly be seen for a precondition. From your Cambridge English Corpus There is not any actual distinction between the standard to start with-order objects in the mathematical discourse - like https://vehicleaccidentrights69135.shoutmyblog.com/34855677/everything-about-canine-arthritis-treatment