American researchers say farmers should wait one day after a rain storm or watering their fields to harvest fresh fruits and vegetables. They say gathering the crops at least 24 hours after rainfall increases food safety. They say it also may be enough to protect those eating from fresh produce from food borne illnesses.

    Listeria(利斯特杆菌) is a food borne bacteria. It grows best in wet conditions. Poisoning with Listeria monocytogenes (单增利斯特菌)can cause muscle pain. The person can also feel sick to the stomach and even experience diarrhea – the uncontrolled expulsion (排除)of wastes from the body.

    Listeria can be a serious health threat for pregnant women and older adults. It can also threaten people with weak immune systems, like those with HIV, the virus responsible for the disease AIDS.

    The bacterium is everywhere in the environment, but usually grows in water. So, crops that are harvested shortly after they have been watered are likely to contain unsafe levels of disease-causing Listeria.

    Martin Wiedmann teaches food safety at Cornell University in New York State. He and other researchers are urging farmers to wait 24 hours after a rainfall or watering fields before they harvest crops. By waiting, he says, a field has enough time to dry out.

    "You're more likely to find Listeria for a very short time. After one day, it drops back more or less to the baseline normal level that we find (in the environment). So, we found this effect in water, but it's very short-lived. Within a day, you are back to normal."

    In crops like spinach(菠菜), Listeria levels were 25 times greater when harvested immediately after the plants were watered.

    Martin Wiedmann notes that Listeria poisoning is less common in developing countries. In such areas, he adds, foods generally are not left in iceboxes or refrigeration equipment, another source of bacterial overgrowth.

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1.Why are the farmers asked to wait one day after a rain to harvest their fresh fruits?

A For the freshness of the fruits.

B For the increase in weight.

C For the safety of people.

D For the food borne illnesses.

解析：选C。C。细节理解题。由第一段可知，为了增加食物安全性，最好是在雨天24小时后采摘蔬菜（C选项）。

2.The food borne bacteria—Listeria will not directly cause__________.

A AIDS

B stomach illness

C muscle pain

D a serious health problem for pregnant women

解析：选A。A。细节理解题。由第二, 三段可知，细菌Listeria不会直接引起AIDS。故选A。

3.The underlined word ‘urging’ in paragraph 5 probably means____________.

A advise

B order

C force

D try

解析：选A。A。词义猜测题。这里表达的应该是研究人员建议农民24小时后采摘蔬菜，以保证食物的安全。故选A。

4.Which of the statements is correct about Listeria?

A In water Listeria is very short-lived.

B Crops that are harvested shortly after rain are sure to contain Listeria.

C There will be no Listeria on the crops one day after watering.

D There will still be some Listeria on the crops one day after watering.

解析：选D。D。推理判断题。Listeria存在于水中，在无水的情况下才存活短，所以A是错误的；B和C说法都太绝对化了；文章中说，24小时后，只是把食物中的Listeria降到正常水平，这说明，在平常情况下，食物中还是含有Listeria的，所以D为最佳选项。

5.What is implied in the last paragraph?

A Listeria develops slower in developing countries.

B Food in iceboxes may increase its risk of Listeria.

C Iceboxes are better than refrigerators in keeping food.

D There is no need to put food in iceboxes or refrigerators.

解析：选B。B。推理判断题。icebox 和refrigerator 指的是同一种东西，即‘冰箱’，而冰箱是Listeria细菌的另一发展源，所以B选项为最佳选项。