On-the-job smoking is a hot issue for both smokers and non-smokers, and many managers now

see smoking as a productivity(生产力) problem. Although some people question whether smoking really affects one's productivity, it has, in fact, been proven that a smoker costs a company more than a non-smoker. According to Professor William Weis, a smoking employee costs his or her employer about $5,700 more a year than a never-smoker. These costs include medical care, lost earnings and insurance. And absence due to smoking breaks is one of the productivity problems, yet it accounts for a great deal of employer costs.

(78)When the issue of smoking at the workplace is discussed, perhaps the most important problem is the health risk that smoking causes to both smokers and never-smokers. It has long been proven that smoking is linked to lung cancer. Now many health experts warn that passive smoking can cause lung cancer and other illnesses in healthy never-smokers. Passive smoking can be defined as exposure to second-hand tobacco smoke in enclosed areas. Anyone who has been with smokers indeed knows that their smoke can cause eye irritation(刺激), coughing, headaches and throat soreness. While eye irritation may seem a small thing to some smokers, it nevertheless is a problem that occurs every workday in offices and break-rooms and can lead to greater health problems. Employees who do not smoke should not be subjected(遭受) to the risks of passive smoking and need to be able to work in a safe environment. Surgeon General Koop states that the right of the smoker stops at the point where his or her smoking increases the disease risk of those occupying the same environment.

All the following cases are on-the-job smoking except that______.

A．an employer smokes while working in the office

B．a taxi driver smokes while driving the car

C．a worker smokes while working in the workshop

D．a worker smokes while reading in the train