新托福听写训练 第15期

Listen to part of the lecture in a health science class.

The professor will be discussing a solution to a health problem caused by a certain parasite¹ sometimes invade humans.

A parasite is an organism that live in or on another organism called the host. During the talk, listen for:

Where the parasite normally lives?

How the parasite affects and harms humans?

How the proposed solution is supposed to work?

Let's look at another way that health agencies fighting parasitic² diseases. One alternative to drugs and pesticides³ is the use of biologic agency. Another word, if the parasite is causing a problem, you find something that eats the parasite itself or something that eats the parasite's normal host. Then you turn that something lose in the parasite's habitat. For example, considering the schistosomisasis. Schistosomisasis is the infection with the parasite worm called schistosome. Normally the host for the schistosome worm is a kind of freshwater snail⁴. But in the African country Kenya the worm frequently infects humans who are exposed to water from ponds where the snail lives. The contact commonly occurs when people get their cattle water or wash their clothes in the ponds. In fact about 2 million Kenyans mostly children are infected. Once inside the human host, the worm lays eggs and these can result internal breeding, fever, fatigue⁵ and sometimes death. The snails⁶ are still necessary as hosts though because schistosome eggs only can hatch inside the snails. If you are already infected, you can take a drug to kill the worms. But the drug is expensive and it's easy to get re-infected when you go back to the ponds. Instead, researchers are trying to eliminate the worm's normal host the snail by introducing Louisiana crayfish into the ponds where worms and the snails live. Now as you can see, a crayfish is something like miniature lobsters⁷ and it loves to eat snails. Snail shells are rich in calcium⁸ which crayfishes need for their own shell. And the crayfishes are already abundant to their natural Kenya rivers, they were imported there in early 1930s, and they are easy to find. So crayfish could end up being a cheap and effective way to reduce receive schistosomiasis. If they do though, it would be the first time a biological agent has been successfully used to control a parasite.

1 parasite   

n.寄生虫；寄生菌；食客

参考例句：

• The lazy man was a parasite on his family.那懒汉是家里的寄生虫。
• I don't want to be a parasite.I must earn my own way in life.我不想做寄生虫，我要自己养活自己。

2 parasitic   

adj.寄生的

参考例句：

• Will global warming mean the spread of tropical parasitic diseases?全球变暖是否意味着热带寄生虫病会蔓延呢？
• By definition,this way of life is parasitic.从其含义来说，这是种寄生虫的生活方式。

3 pesticides   

n.杀虫剂( pesticide的名词复数 )；除害药物

参考例句：

• vegetables grown without the use of pesticides 未用杀虫剂种植的蔬菜
• There is a lot of concern over the amount of herbicides and pesticides used in farming. 人们对农业上灭草剂和杀虫剂的用量非常担忧。 来自《简明英汉词典》

4 snail   

n.蜗牛

参考例句：

• Snail is a small plant-eating creature with a soft body.蜗牛是一种软体草食动物。
• Time moved at a snail's pace before the holidays.放假前的时间过得很慢。

5 fatigue   

n.疲劳，劳累

参考例句：

• The old lady can't bear the fatigue of a long journey.这位老妇人不能忍受长途旅行的疲劳。
• I have got over my weakness and fatigue.我已从虚弱和疲劳中恢复过来了。

6 snails   

n.蜗牛；迟钝的人；蜗牛( snail的名词复数 )

参考例句：

• I think I'll try the snails for lunch—I'm feeling adventurous today. 我想我午餐要尝一下蜗牛——我今天很想冒险。 来自《简明英汉词典》
• Most snails have shells on their backs. 大多数蜗牛背上有壳。 来自《简明英汉词典》

7 lobsters   

龙虾( lobster的名词复数 )； 龙虾肉

参考例句：

• I have no idea about how to prepare those cuttlefish and lobsters. 我对如何烹调那些乌贼和龙虾毫无概念。
• She sold me a couple of live lobsters. 她卖了几只活龙虾给我。

8 calcium   

n.钙(化学符号Ca)

参考例句：

• We need calcium to make bones.我们需要钙来壮骨。
• Calcium is found most abundantly in milk.奶含钙最丰富。