"Echo?"
"Yes, it felt like he was standing in a sealed, empty house."
Zhang Guanxing gestured with his hand, "Over the phone, he told me he was fine, studying in the classroom, and told me not to worry."
"I thought to myself that this guy really had changed, he used to run out of class faster than anyone, not willing to stay in the classroom for a second longer, and now he continued to study there after school. No wonder his grades had improved dramatically."
"Hearing his tone, there was nothing abnormal, and he even joked with me, so my unease gradually disappeared."
"What really made me feel there was a problem was when, later that night, around eleven, I called him again."
"The sound on the other end was muffled. I asked what he was doing, and he actually said he was still studying in the classroom!"
"The classrooms are locked and lights out by that time; how could he possibly still be studying there?"