Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks.
Any change in one part of an ecosystem can cause changes in other parts. Droughts, storms and fires can change ecosystems. Some changes (1) _______ ecosystems. If there is too (2) _______ rainfall, plants will not have enough water to live. If a kind of plant dies off, the animals that feed on it may also die or move away. Some changes are good for ecosystems. Some pine forests need fires for he pine trees to reproduce. The seeds are sealed inside pinecones. Heat from a forest fire melts the seal and lets the seeds (3) _______. Polluting the air, soil, and water can harm ecosystems. Building (4) _______ on rivers for electric power and irrigation can harm ecosystems around the rivers. Bulldozing wetlands and cutting down forests destroy ecosystems. Ecologists are working with companies and governments to find better ways of (5) _______ 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.
Điền vào ô số 4
A. moats
B. ditches
C. bridges
D. dams
Đáp án D.
Tạm dịch: Building (4) _______ on rivers for electric power and irigation can hảm ecosystems around the rivers: Xây _______ trên sông làm thủy điện và tưới tiêu cũng gây hại tới hệ sinh thái xung quanh dòng sông.
A. moats: hào (xung quanh thành trì)
B. ditches: (hào, rãnh, mương)
C. bridges: cầu
D. dams: đập
Xây đập trên sông để làm thủy điện và phục vụ tưới tiêu do đó đáp án đúng là D. dams.