The place where Zhang Ping'er was bitten by a poisonous snake was...her buttocks!
It's no wonder that Zhang Xiaohua failed to notice, when he spotted Zhang Ping'er, she was lying on the ground. He was focused on inspecting her injuries, so it's natural he didn't take a close look at that area. Moreover, it doesn't seem appropriate for a young man like him to blatantly stare at that part of a woman's body!
When Zhang Xiaohua turned Zhang Ping'er over, it completely obscured his view. Naturally, he didn't consider the possibility of a snake biting her there. So, when he discovered where Zhang Ping'er's injury was, he couldn't help but smirk bitterly.
However, even so, Zhang Xiaohua did not dare to delay. The deadly poison, that even the antidote pill of Xiang Sect couldn't cure, was indeed dangerous. Although the detoxification pill he made was effective, if the residual poison in her body was not promptly eliminated, all his previous efforts might go in vain.
