Last week, 169 Junior 1 students at No. 35 Middle School of Shenyang took their first no-teacher exam. After the teacher handed out the exam paper, he left the room and never came back. A student collected in the papers when the exam ended.
   "That test was not only a test of knowledge, but also a test of moral(道德). We wanted to show students how important honesty is, "said Cai Wenguo, the school's headmaster. The school says no cheating (作弊)happened in the test. Next year, it wants 80％ of its exams to be without teachers. But students have different ideas.
   “I was happy and excited during the exam because my teachers trusted me, "said Lang Yudan, a 13-year-old girl in Class 11.
   “Schools must trust students a lot not to use invigilators（监考人）. But I think it is too early. Some students will cheat if there are no invigilators. And the students will not be able to ask for help when needed. "said Hua Sha.
   “I don't like having invigilators in exams. When they walk around the classroom, they make me nervous. I would get higher marks without them in the room because I would feel more relaxed. "Liu Qingxi said.
   “I think it's very important to have invigilators in exams. Many students want to check their answers with each other after they have finished papers. And they can also keep the classroom in order when something unusual happens. They may make me nervous, but I still think we need them. "Shangguan Yuan said.
   Not using invigilators may be a good idea. But before using it, schools must tell students the importance of honesty and try to find ways to solve something unusual in exams.

昆虫的保护色越来越逼真，它们的天敌的视觉也越来越发达，结果双方都没有取得明显的优势.说明