题目

完形填空 One student took a box of chicken to class. Another carried on a cell-phone1and still another whistled loudly every time the2turned his back. Reform school? No. College. More and more, professors say, they are3 across rude students in their classrooms. Many of today's young scholars arrive late, leave4talk loud or take care of personal 5such as paying bills during class. Why are the students behaving badly? “Because they can,” said a student of University of North Texas. “A lot of the time, the professors 6them get away with it.” Some educators say it is time to bring pol20．以下四幅元素含量示意图与文字描述对应正确的是（　　）A．人体中B．海水中C．地壳中D．丙氨酸（C3H7O2N）中