题目

When you feel a sneeze or a cough coming on, covering your mouth prevents the spread of infectious germs(细菌). You probably knew that. But the way you cover up also matters, and there are plenty of people who haven’t yet heard the advice from health officials: If no tissue is available, you should aim into your elbow(肘部), not your hand. Even if that means breaking a long-held habit.If somebody sneezes into their hands, that creates an opportunity for those germs to be passed on to other people, or pollute other objects that people touch, said Dr. Vincent Hill, of the Centers for Disea19．新学期开学之际，有A，B，C，D，E共5名同学同时考入某校高一年级，已知该校高一年级共有6个班，则每个班最多有这5名同学中的2名同学的不同情况共有（　　）A．4200种B．4320种C．6120种D．7920种