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theblueknight1311
2 năm trước
Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.
Graham was disappointed because he _______ for the bus for an hour.




A.was waiting
B.waited
C.has been waiting
D.had been waiting
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Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions
The development of genetically modified (GM) plants and animals had led to a huge global controversy. Opponents say that GM “Franken foods” are a threat to our well-being, and proponents say that the risks are minimal. There is one aspect of the war over GM that is often overlooked. Anyone who wears a cotton shirt these days is using a GM crop. Cotton is the only major non-food GM crop at present, but others are coming.
GM cotton plants that is not food has not stopped the most passionate GM opponents from objecting. If GM cotton is grown in a field next to fields of non-GM cotton, they argue, then how to keep genes from being transferred from field to field. This danger, however, is not as compelling to the public as possible health hazards in food, so there is no great fury over GM cotton.
GM cotton seeds produce higher yields, and they do without the need for pesticides. Planting of GM cotton has increased five fold since 1997; three-quarter of cotton in America, and over half in China, is now GM. Farmers like it because it increases their profits.
Other options for non-food GM include new variety of flowers with different colors or scents, tougher grasses for lawns, and plants designed to soak up pollutants from the soil. The paper industry provides another example of potential for GM to help produce better and cheaper products. Paper is made from pulp, and pulp is generally made from trees. Researchers in New Zealand and Chile have been working on insect-resistant pines, and a Japanese firm has combined carrot genes with tree genes to make them grow better in poor soil.
Another interesting case is that of tobacco. It is not food crop, but it is consumed, and GM tobacco plants with both more and less nicotine have been created. The tobacco plant, however, is an ideal target for GM, since its genetics are very well understood and it produces a lot of leaves. The value of the drugs that could be produced by GM tobacco is so high, many farmers could switch from growing tobacco for cigarettes to growing it for medicine. Since medical cost is rising, consumers would also be happy to use drugs produced in bulk by GM tobacco.
It can be inferred from the passage that GM tobacco




A.can have lower or higher levels of nicotine.
B.produces drugs that are very expensive.
C.makes cigarettes harmless to smokers.
D.is already in the market.

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