题干

下列有关氟氯代烷的说法中,不正确的是:

A:氟氯代烷是一类含氟和氯的卤代烃

B:氟氯代烷化学性质稳定,有毒

C:氟氯代烷大多无色、无臭、无毒

D:在平流层中,氟氯代烷在紫外线照射下,分解产生的氯原子可引发损耗臭氧的循环反应

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答案(点此获取答案解析)

B

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    Everyone takes drugs. Sometimes a drug might be called a herb but the effect is the same. Drugs and herbs can make life better for they are used to improve health. From the simplest headache to a cure for cancer, people believe that certain drugs can help them. But there is danger if the drugs are not used in a proper way.

    American teenagers sometimes use certain drugs to feel good. They call this “getting high”. The problem is that once a young man or a young woman has the feeling of “getting high”, they want to do it often. If school is boring or too hard, students might get depressed and a drug or herb might help them feel better. If the student takes too much of a drug, the body may change in a wrong way such as a confused mind, poor sight, a headache, and an uncomfortable stomach.

    Schools now have D.A.R.E.program which means Drug Abuse Resistance Education. This program was started so that young students from age 10 to 18 might understand how a drug affects their bodies. The main point of the program is education. Once a student understands certain drugs can cause ill health,he will know he should not use them.

    Education is the key to good nutrition as well. If a student eats correctly, he or she will be full of energy which leads to good study habits and good grades. Poor nutrition may cause the need for more sleep and poor concentration. Proper food is similar to the proper use of drugs. Both allow a healthy body to grow while misuse of them prevents a person from developing normally.