Directions:

　　For each blank in the following passage, there are four choices given below and marked A, B, C and D. Choose the one that is most suitable and mark your answer by blackening the corresponding letter on the Answer Sheet.

　　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.

　　51.A. Still B. Further C. More D. Again

　　52.A. in B. to C. on D. with

　　53.A. polluting B. be polluted C. polluted D. to be polluted

　　54.A. them B. themselves C. their own D. they

　　55.A. and B. but C. as well as D. also

　　56.A. where B. which C. that D. how

　　57.A. feeling B. sense C. realize D. think

　　58.A. so B. next C. therefore D. and

　　59.A. non-smokers B. non-smokers’ C. non-smoker’s D. non-smoker

　　60.A. number B. amount C. many D. much