题目内容：

5-second rule:what’s the truth?

Almost everyone has dropped some food on the floor and still wanted to eat it. If someone saw you drop it, he or she might have shouted, “5-second rule!”This so-called rule says food is OK to eat if you pick it up in five seconds or less. But is that true?

Professor Anthony Hilton from Ashton University, UK, tested the rule with his students. They found that food dropped for five seconds is less likely to contain bacteria(细菌) than if it sits there for longer.

For the study, Hilton and his students tested a lot of food—bread, pasta, cookies and candy—to see how much bacteria they had when they made contact with the floor. They allowed the food to lie on various types of flooring-carpet, laminate(复合地板), and tile (瓷砖) for three seconds to 30 seconds.

Not surprisingly, the longer the food was on the floor, the more bacteria it had. And the type of floor where the dropped food landed had an effect. Bacteria are least likely to transfer from carpet, while they’re most likely to transfer from laminate or tiled surfaces after more than five seconds.

The study also found that the wetter the food, the more likely it was to pick up bacteria. Although most people are happy to follow the 5-second rule, eating food dropped on the floor still carried an infection(感染) risk. “It very much depends on which bacteria are on the floor at the time,” Hilton told Forbes.

1.What is the “5-second rule” about?

A. People often shout at someone when they drop food on the floor.

B. Food is safe when you pick up off the floor in less than five seconds.

C. It’s better to eat dropped food when it’s been on the floor for over five seconds.

D. Food will go bad when dropped on the floor in five second or less.

2.Hilton’s test wanted to find out ________.

A. if the “5-second rule” is true    B. the students’ favourite food

C. which food is easily dropped    D. if different types of floor have different bacteria

3.According to the test, we learn the following EXCEPT ________.

A. the dropped food had more bacteria if it sat on the floor for longer

B. the dropped food on carpet had the least bacteria

C. bacteria was impossible to transfer from laminate or tied surfaces

D. the wetter food was more likely to pick up bacteria

4.According to the article, the infection risk of the dropped food does NOT depend on _______.

A. how long the food sits on the floor    B. what the dropped food was

C. what the bacteria are    D. what the weather is like that day