An alcohol breath test (ABT) is often used by the police to find out whether a person is drunk while driving. In the United States, the legal blood alcohol limit is 0.08% for people aged 21 years or older, while people under 21 are not allowed to drive a car with any level of alcohol in their body. A “positive” test result, a result over the legal limit, allows the police to arrest the driver. However, many people who tested positive on the test have claimed that they only drank a “non-alcoholic” energy drink. Can one of these energy drinks really cause someone to test positive on an ABT? Researchers in Missouri set up an experiment to find out.
First, the amount of alcohol in 27 different popular energy drinks was measured. All but one had an alcohol level greater than 0.005%. In nine of the 27 drinks, the alcohol level was at least 0.096%.The scientists then investigated the possibility that these small levels of alcohol could be discovered by an ABT. They asked test subjects to drink a full can or bottle of an energy drink and then gave each subject an ABT one minute and 15 minutes after the drink was finished.
For 11 of the 27energy drinks, the ABT did find the presence of alcohol if the test was given within one minute after the drink was taken. However, alcohol could not be discovered for any of the drinks if the test was given 15 minutes after the drink was consumed. This shows that when the test is taken plays an important role in the test result. The sooner the test is conducted after the consumption of these drinks, the more likely a positive alcohol reading will be obtained.
39. What is the legal alcohol level for a 20-year-old driver in the US?
A. 0.000%. B. 0.005%. C. 0.080%. D. 0.096%.
40. What is the purpose of the 
Missouri experiment?
A. To warn people of the dangers of drinking energy drinks.
B. To introduce a new method of calculating blood alcohol levels.
C. To discover the relation between energy drinks and ABT test results.
D. To change the current legal alcohol limit for drivers in the United States.
41. The underlined word “subjects” in Paragraph 2 refers to_____.
A. the things that are being discussed B. areas of knowledge studied in school
C. the person in an experiment D. the people who belong to a country
42. Which of the following affects the ABT test result most for energy drink consumers?
A. The age of the person who takes the test.
B. The place where the test is given.
C. The equipment that the test uses.
D. The time when the test is taken.