Read the article and select the best answer. Article: At least 10 million hectares of cultivated land in China are polluted, which makes a _ threat to the country's food safety, the Xinhua News Agency reported on Friday. The polluted land,which is mostly in economically developed areas,accounts for one-tenth of the country's total arable land,according to an incomplete survey by the State Environmental Protection Administration,China's top environment watchdog. Pollution on cultivated land threatens the environment,food safety and the sustainable development of agriculture,the administration said. Because of continual,too much use of chemical fertilizer, pesticide and agricultural plastic sheeting, as well as irrigation using polluted water, a large amount of contaminants remain in the cultivated land. The contaminants affect the soil's ecological structure and function,leading to decreased soil productivity, lower crop yield ,and lower quality of agricultural products- It also leads to worse water quality in rural areas. Less than 9 per cent of drinkable water passed checks for bacteria in243 rural water supply stations across the county. Another survey, which took samples of drinking water and groundwater an 69 small towns. in Beijing, Tianjin and Hebei Province of North,China, showed that more than half of the water contains too much nitrate ,which may cause diabetes and damage the kidney. The administration estimated at least 1 90 million farmers are drinking water that contains harmful substances. Many villagers drink unfiltered water taken from shallow water wells or water cellars, which are reported to have poor sanitary conditions* Question: Pollution on cultivated land leads to the following outcomes EXCEPT _ . Options: A: a threat to China's food safety B: worse water quality in rural areas C: a variety of diseases D: the sustainable development of agriculture
D

(Question)
Read the article and select the best answer. Article: Fish have ears. Really. They're quite small and have no opening to the outside world carrying sound through the body. For the past seven years, Simon Thorrold, a university professor, has been examining fish ears, small round ear bones called otoliths. As fish grow, so do their otoliths. Each day, their otoliths gain a ring of calcium carbonate . By looking through a microscope and counting these rings, Thorrold can determine the exact age of a young fish. As a fish gets older, its otoliths no longer get daily rings. Instead, they get yearly rings, which can also be counted, giving information about the fish's age, just like the growth rings of a tree. Ring counting is nothing new to fish scientists. But Thorrold has turned to a new direction. They're examining the chemical elements of each otolith ring. The daily ring gives us the time, but chemistry tells us about the environment in which the fish swam on any given day. These elements tell us about the chemistry of the water that the fish was in. It also says something about water temperature, which determines how much of these elements will gather within each otolith ring. Thorrold can tell, for example, if a fish spent time in the open ocean before entering the less salty water of coastal areas. He can basically tell where fish are spending their time at any given stage of history. In the case of the Atlantic croaker, a popular saltwater food fish, Thorrold and his assistant have successfully followed the travelling of young fish from mid-ocean to the coast, a journey of many hundreds of miles. This is important to managers in the fish industry, who know nearly nothing about the track of the young fish for most food fish in the ocean. Eager to learn about his technology, fish scientists are now lending Thorrold their ears. Question: Why does the writer compare the fish to trees? Options: A: Trees gain a growth ring each day. B: Trees also have otoliths. C: Their growth rings are very small. D: They both have growth rings.
(Answer)
D

Ques:Read the article and select the best answer. Article: It's impolite to spit out the first bite of your dinner. But to a type of Australian snake, this rude behavior is a matter of life and death. The snake, called a floodplain death adder , eats two types of frogs that are hard to stomach. The frogs produce chemicals to defend them from predators . One of these species, the Dahl's frog, can kill a snake that tries to eat it. The other species, the marbled frog, is less dangerous but still tough to eat. When attacked, _ produces a glue like substance. Leaves and branches get caught up in this material, making a big sticky mess that gets in the way of anything trying to swallow it. A marbled frog can even get stuck on the head of an attacking snake. Both frogs have good defense methods. But the floodplain death adder knows how to get around each of them. Floodplain death adders quickly strike these frogs, using their poisonous teeth to inject poison. But then, instead of swallowing their dinner immediately, the snakes sit back and wait for their preys to become safe to eat. That's because both the Dahl's frog's protective toxin and the marbled frog's glue break down over time. After a while, the frog toxin is no longer poisonous and the glue is no longer sticky. The two substances break down at different rates, and floodplain death adders seem to know the difference, And adder waits for a different length of time depending on the species of frog it just struck. The stickiness of the marbled frog glue decreased by as much as two-thirds after just 10 minutes. And that's just about how long an adder waits before eating a marbled frog. On the other hand, the snakes wait for about 40 minutes before eating a Dahl's frog. That's enough time for the frog's toxin to break down into harmless substances. But even a quick strike gives a taste of the Dahl frog's toxin. After striking such a frog, a floodplain death adder thrashes around and lies on its back with its mouth open, It's like the snake has just had a... Question: What's the floodplain death adder's method to make the frogs safe to eat ? Options: A: They thrash around with their mouths open B: They sit back and wait for their preys to become safe to eat C: They inject poison on the preys and wait for the breaking down of their toxin and glue before eating them D: They quickly strike these frogs

Ans:
C