Don't Be So Sure

Zhang Heng's clone curiously glared at the knife stuck in his thigh, his face showing no sign that he was in any pain. "It seems I have to take back what I said before," he said calmly. "You are no smarter than your peers. Since you already know what I am, you should know that such torture wouldn't affect me. If you are intending to use such means to extract information, I advise you not to waste your energy."

"No, don't get me wrong, I did this because I wanted to. There is no other purpose." Zhang Heng stopped for a moment. "Okay, let's go to the next topic. Before that, let me ask you a warm-up question."

"And what would this question be?" The clone rolled his eyes.

"I want to know what medium you used to contact your people?"

"What do you mean by the medium that I use?" The clone rubbed his chin on his shoulder.

"Think about a bat's ultrasonic soundwave."