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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 from 36 to 42.

The geology of the Earth's surface is dominated by the particular properties of water. Present on Earth in solid, liquid, and gaseous states, water is exceptionally reactive. It dissolves, transports, and precipitates many chemical compounds and is constantly modifying the face of the Earth.

Evaporated from the oceans, water vapor forms clouds, some of whichare transported by wind over the continents. Condensation from the clouds provides the essential agent of continental erosion: rain. Precipitated onto the ground, the water trickles down to form brooks, streams, and rivers, constituting what are called the hydrographic network. This immense polarized network channels the water toward a single receptacle: an ocean. Gravity dominates this entire step in the cycle because water tends to minimize its potential energy by running from high altitudes toward the reference point, that is, sea level.

The rate at which a molecule of water passes though the cycle is not random but is a measure of the relative size of the various reservoirs. If we define residence time as the average time for a water molecule to pass through one of the three reservoirs - atmosphere, continent, and ocean - we see that the times are very different. A water molecule stays, on average, eleven days in the atmosphere, one hundred years on a continent and forty thousand years in the ocean. This last figure shows the importance of the ocean as the principal reservoir of the hydrosphere but also the rapidityof water transport on the continents.

A vast chemical separation process takes places during the flow of water over the continents. Soluble ions such as calcium, sodium, potassium, and some magnesium are dissolved and transported. Insoluble ions such as aluminum, iron, and silicon stay where theyare and form the thin, fertile skin of soil on which vegetation can grow. Sometimes soils are destroyed and transported mechanically during flooding. The erosion of the continents thus results from two closely linked and interdependent processes, chemical erosion and mechanical erosion. Their respective interactions and efficiency depend on different factors.

Câu 36: The word "which” in paragraph 2 refers to_____________.

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 from 31 to 35.

Jacques-Yves Cousteau was an explorer, ecologist, filmmaker, inventor and conservationist. He was a man, who spent nearly his whole life underwater exploring the hidden depths of the ocean and who did more to educate the world about the mysteries of the deep sea than any other scientist before or since. He was born in June, 1910 in the village of Saint-André-de- Cubzac, in south western France. Jacques was a sickly boy and spent much of his time in bed, reading books and dreaming about a life at sea. In 1920, Jacques' family moved to New York and he was encouraged to start swimming to build up his strength. This was the beginning of his fascination with water and the more he learnt through his own experiences, the more passionate he became about "looking through nature's keyhole". Nevertheless, his career in underwater exploration came about by accident. After entering France's naval academy and travelling around the world, he was involved in an almost fatal car accident that left him seriously injured with two broken arms. He began swimming in the Mediterranean Sea to strengthen his arm muscles as part of his recovery process and rediscovered his love of the ocean. Cousteau developed a pair of underwater breathing apparatus to allow him to stay underwater for long periods of time. His experiments led to the development of the first Aqua¬Lung which was a great commercial success. During World War II, he worked for the French Resistance and experimented with underwater photographic equipment. He helped to get rid of German mines and was awarded the Legion D'Honneur and the Croix de Guerre medals for his bravery. In 1942, he filmed his first underwater film Sixty Feet Down. It was 18 minutes long and was entered in the Cannes Film Festival.

Câu 31: What is the writer trying to do in the passage?