After a study showed that one in every ten meals in the country may be cooked in with dirty oil, the State Food and Drug Administration (SFDA) on Thursday issued an emergency notice （发布紧急通知）to restaurants nationwide, warning them against recycling oil.
The swill-oil is cooking oil refined from kitchen waste that has been recycled. Although it looks clean and clear, it’s actually so dangerous to people’s health that it may cause cancer.
According to a report, the swill-oil business is extremely profitable. Recycling one ton of kitchen waste will produce 130 kg of swill oil. With its price being half that of normal cooking oil, a profit（利润）of 1.5 to 2 billion yuan is produced in the whole swill-oil business in the country every year. The profit is almost 200%, so it’s easy to understand why the business is so hot.
He Dongping, a professor from Wuhan Polytechnic(WHPU) said, “To stop the use of dirty oil should start at its source, kitchen waste. And the first step is to find a good way of collecting kitchen waste.” “However, it might take about 10 years before China could solve the problem completely,” he added.

According to the study, ______ of us may have eaten the food cooked by dirty oil.
A. few            B. nobody        C. many
The underlined sentence “the swill-oil business is extremely profitable” means that the swill-oil business is really a ________.
A. big money-maker
B. common situation
C. terrible thing
We can infer（推断）from this passage that _______.
A. the biggest problem is that restaurants produce too much kitchen waste.
B. the way of dealing with kitchen waste isn’t good enough now.
C. we can stop the use of swill-oil in a short time if we take it serious.
The main topic of this passage is about _______.
A. restaurant service
B. food safety
C. eating habits