THOUSANDS PEOPLE JOINED THE ARMY WHEN THE COUNTRY WAS AT WAR. A. JOIN...

Câu 28: Thousands people joined the army when the country was at war.

A. joined B. the army C. at war D. thousands people

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.

Human Nutrition is the study of how food affects the health and survival of the human body. Human

beings require food to grow, reproduce, and maintain good health. Without food, our bodies could not

stay warm, build or repair tissue, or maintain the heartbeat. Eating the right foods can help us avoid

certain diseases or recover faster when illness occurs. These and other important functions are fueled by

chemical substances in our food called nutrients. Nutrients are classified as carbohydrates, proteins, fats,

vitamins, minerals, and water.

When we eat a meal, nutrients are released from food through digestion. Digestion begins

in the mouth by the action of chewing and the chemical activity of saliva, a watery fluid that contains

enzymes, certain proteins that help break down food. Further digestion occurs as food travels through the

stomach and the small intestine, where digestive enzymes and acids liquefy food and muscle contractions

push it along the digestive tract. Nutrients are absorbed from the inside of the small intestine into the

bloodstream and carried to the sites in the body where they are needed. At these sites, several chemical

reactions occur, which ensures the growth and function of body tissues. The parts of foods that are not

absorbed continue to move down the intestinal tract and are eliminated from the body as feces.

Once digested, carbohydrates, proteins, and fats provide the body with the energy it needs to maintain

its many functions. Scientists measure this energy in kilocalories, the amount of energy needed to raise

one kilogram of water one degree Celsius. In nutrition discussions, scientists use the term calorie instead

of kilocalorie as the standard unit of measure in nutrition.

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Nutrients are classified as essential or nonessential. Nonessential nutrients are

manufactured in the body and do not need to be obtained from food. Examples include cholesterol, a

fatlike substance present in all animal cells. Essential nutrients must be obtained from food sources,

because the body either does not produce them or produces them in amounts too small to maintain growth

and health. Essential nutrients include water, carbohydrates, proteins, fats, vitamins, and minerals.

An individual needs varying amounts of each essential nutrient, depending upon such factors as

gender and age. Specific health conditions, such as pregnancy, breast-feeding, illness, or drug use, make

unusual demands on the body and increase its need for nutrients. Dietary guidelines, which take many of

these factors into account, provide general guidance in meeting daily nutritional needs.