A single cannabis joint (大麻烟卷) may cause as much damage to the lungs as five chain-smoked cigarettes,research has found. Medical examinations of cannabis and tobacco smokers found the drug increased lung problems.

Smoking one cannabis cigarette caused damage equal to smoking 2. 5 to 5 tobacco cigarettes,researchers at the Medical Research Institute ofNew Zealandfound. Doctors who carried out the study believe the greater damage is connected with the difference in the way cannabis is usually smoked,with users inhaling hard,holding their breath longer and failing to use filters.

The scientists began to look into whether smoking cannabis put users in greater danger of developing emphysema (肺气肿) .

A group of 339 volunteers aged 18 to 70 were divided into four groups according to whether they smoked only cannabis,only tobacco,both,or were non-smokers. Each volunteer went through lung function tests and X-ray scans(扫描) of their chests to measure the level of damage to their lungs and airways.

In the study,published in the journal Thoraxall smokers had coughs and wheeze(气喘) ,while only tobacco smokers showed signs of emphysema. Coughing reduced among people who smoked cannabis and tobacco,possibly because these people smoked pure cannabis cigarettes.

The level of lung damage was directly related to the number of cigarettes

smoked. “The most important finding was that one cigarette of cannabis was

similar to the effect of 2. 5 to 5 tobacco cigarettes in causing airflow obstruc-tion(阻碍) ,” the authors stated. “This pattern is likely to be related to the different characteristics(特征) of the cannabis cigarette and the way in which it is smoked. ”

“Cannabis is usually smoked without a filter,and is smoked at a higher temperature,”they added.

1. What would be the main idea of the passage?

   A. Cannabis cigarettes damage lungs more than tobacco cigarettes.

   B.  Cannabis cigarettes are more dangerous than tobacco cigarettes.

   C.  Medical examinations of cannabis and tobacco smokers.

   D.  Cannabis cigarettes damage the lungs as much as tobacco cigarettes.

2. The underlined word “inhaling ” in Paragraph 2 probably means “     

   A. breathing out   B. breathing in

   C.  breathing   D. smelling

3. According to the research,smoking cannabis cigarettes caused greater damage to lungs mainly because          .

   A. cannabis cigarettes contain more dangerous chemical substances

   B.  smoking cannabis can increase the danger of developing lung cancer

   C.  the way cannabis is usually smoked is different and special

   D.  cannabis is more addictive

4. Which of the following statements is TRUE according to the passage?

   A. Tobacco smokers have a greater danger of developing emphysema.

   B.  The study shows that all volunteers tested have coughs and short breath.

   C.  Tobacco cigarettes cause greater airflow obstruction than cannabis cigarettes.

   D.  Cannabis should be smoked without a filter.

5. If the passage appears in a newspaper,which section is the best suitable one?

   A. Education Section.

   B.  Show Section.

   C.  Environment Section.

   D.  Health Section.

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