根据材料回答下列各题,Smoking, which may be a pleasure for some people, is a serious source

of discomfort for their fellows. _51_, medical authorities express their concern about the effect of smoking _52_ the health not only of those who smoke but also of those who do not. In fact, non-smokers who must involuntarily inhale (吸入) the air _53_ by tobacco smoke may suffer more than the smokers _54_. Smoking is prohibited in the theatres and in halls used for showing films _55_ in laboratories _56_ there may be a fire hazard (危险). Elsewhere, it is up to your good _57_. I am _58_ asking you to maintain “No-Smoking” in classrooms and seminar rooms. This will prove that you have the _59_ health in mind, which is very important to a large _60_ of our students.

A.Still

B.Further

C.More

D.Again