任務(wù)型閱讀 When we think of harvests (收獲),we usually think of plants.But can you also harvest
　　When we think of harvests (收獲),we usually think of plants.But can you also harvest a liquid?Sure.Just think of rainwater.Best of all,it is free,except for the cost of a way to collect it.
　　One way to harvest rainwater is with some technology developed by International Development Enterprises.It is in the American state of Colorado.It created the technology as a way for people in developing countries to avoid having to drink polluted (污染) ground water.
　　The rainwater harvesting system (系統(tǒng)) created by International Development Enterprises uses pipes (管子) to collect water from the tops of buildings.There are pipes between the buildings and two-meter tall storage tank (存儲容器),which prevents dirt and leaves in the water from falling inside the tank.
　　A cover sits over the tank.It protects the water inside the tank from evaporating (蒸發(fā)).The cover also prevents insects (昆蟲) from flying into the water and laying eggs.
　　Inside the tank is a low-cost plastic bag that collects the water.The bag sits inside another plastic bag.The two bags are supported (支撐) inside the metal tank.In all,the tank can collect to 3,500L of water.
　　International Development Enterprises says the bags inside the tank may need to be replaced every two to three years.However,if the bags are not damaged (損壞) by sunlight,they could last even longer.
　　The developers say one tank can provide a family of five with enough rainwater to go through a five-month dry season.
　　13.Can people harvest rainwater according to the passage?
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　　14.What is the biggest advantage of storing rainwater with the technology?
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　　15.How much water can the tank keep?
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　　16.What is the cover on the tank used for?
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　　17.What’s the main idea of the passage?
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