As a result of pollution, Lake Erie, on the borders of the USA and Canada, is now without any living things. Pollutions in water are not simply a matter of “poisons” killing large numbers of fish overnight. Very often the effects of pollution are not noticed for many months or years because the first organisms to be affected are either plants or plankton. But these organisms are the food of fish and birds and other creatures. When this food disappears, the fish and birds die in this way a whole food chain can be wiped out, and it is not until dead fish and water birds are seen at the river’s edge or on the sea shore that people realize what is happening. Where do the substances which pollute the water come from? There are two main sources – sewage and industrial waste. As more detergent is used in the home, so more of it is finally put into our rivers, lakes and seas. Detergents harm water birds dissolving the natural substance which keep their feather waterproof. Sewage itself, if it is not properly treated, makes the water dirty and prevents all forms of life in rivers and the sea from receiving the oxygen they need. Industrial waste is even more harmful since there are many high poisonous things in it, such as copper and lead. So, if we want to stop this pollution, the answer is simple, sewage and industrial waste must be made clean before flowing into the water. It may already be too late to save some rivers and lakes, but others can still be saved if the correct action is taken at once.

What is the meaning of “waterproof” in the second paragraph?

Câu hỏi liên quan

• The word ‘monumental’ in Paragraph 2 means ..............

• Throughout the passage, the author implies that the Mandans _____.

• In the author’s judgment, ...............

ZUNIA12

• The word "derived" in line 13 is closest in meaning to ____________.

• It is ............ to write the rules that tell exactly when we should apologize.

• The word "analogue" in paragraph 5 most nearly means_____.

• Who called the apelike creatures 'Sasquatch'?

• The author uses the word “But” in paragraph 4 to ______.

• The word “hurdles” can be best replaced by ___________.

• The word "drastically" in line 21 is closest in meaning to ..........

• The seashore was a barrier for descendants of fish-type because………

• What happened when he saw the jumbo jet for the first time?

• According to the passage, which type of memory is the shortest?

• The word "grip" in the passage means to ..........

• According to the passage, which of the following is NOT true about primitive art?

• The word “immense” in paragraph 3 is closest in meaning to ______.

• Which form other than oral speech would be the most commonly used among blind people?

• The author states that "On the average, people can keep about seven ideas in their minds at once" (paragraph 3) to explain that .....

• In compared with low-achieving students, successful students use ...........

• What do officials do during the game of football?