Read the following passage, and mark the letter A, B, C, or D on your answer sheet to indicate the correct word for each of the blanks from 19 to 28.
Any change in one part of an ecosystem can cause changes in other parts. Droughts, storms and fires can change ecosystems. Some changes ___ 19 ___ ecosystems. If there is too ___ 20 ___ rainfall, plants will not have enough water to live. If a kind of plant dies off, the animals that ___ 21 ___ it may also die or move away. Some changes are good for ecosystems. Some pine forests need ___ 22 ___ for the pine trees to reproduce. The seeds are sealed inside pinecones. Heat from a forest fire melts the seal and lets the seeds___ 23 ___. Polluting the air, soil, and water can harm ecosystems. Building ___ 24 ___ on rivers for electric power and irr igation can harm ecosystems ___ 25 ___ the rivers. Bulldozing wetlands and cutting down ___ 26 ___ destroy ecosystems. Ecologists are working with companies and governments to find better ways of ___ 27 ___ fish, cutting down trees, and building dams. T hey are looking for ways to get food, lumber, and other products for people ___ 28 ___ causing harm to ecosystems.
Điền vào số 28
A. avoid
B. without
C. not
D. no
Đáp án B
without + N/V-ing: với không …