Read the passage and choose the best option to complete each blank. 
Any change in one part of an ecosystem can cause changes in other parts. Droughts, storms and fires can change ecosystems. Some changes ____46___ ecosystems. If there is too little rainfall, plants will not have enough water to live. If a kind of plant dies off, the animals____47___feed on it may also die or move away. Some changes are good for ecosystems. Some pine forests need fires for the pine trees to reproduce. The seeds are sealed inside pinecones. Heat from a forest fire melts the seal and lets the seeds ____48___. Polluting the air, soil, and water can harm ecosystems. Building dams on rivers for electric power and irrigation can harm ecosystems ____49___ the rivers. Bulldozing wetlands and cutting down forests destroy ecosystems. Ecologists are working with companies and governments to find better ways of ___50____ fish, cutting down trees, and building dams. They are looking for ways to get food, lumber, and other products for people without causing harm to ecosystems
(47)..............

Câu hỏi liên quan

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  I haven't got enough money to buy a new car.

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ZUNIA12

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  There were no poor performance. Moreover, that of the Russian dancers was certainly the best.  

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  He had just finished eating his breakfast. Then he fell down

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• Mark the letter A, B, C, or D to indicate the sentence that is CLOSEST in meaning to each of the following questions.

  He prevented his close friend from telling the truth.

• Choose the correct answer to complete the sentence. " His optimism in his illness went beyond his family's ________.'

• Mark the letter A, B, C, or D to indicate the sentence that is CLOSEST in meaning to each of the following questions.

   I don’t remember the man. You met him at the canteen last week.

• Rewrite: Residents of the area like to go to the park to enjoy a tea break after taking a walk along the shore

• Rewrite: 

  I think you should stop smoking.

• Make the best choice

  After fighting the fire for 12 hours, the firemen succeeded in putting it out.