题目内容
（请给出正确答案）
In Paragraph 2, The word their in the passage refers to
A．brakes.
B．skis.
C．ski manufacturer.
D．kick-off force.
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更多“In Paragraph 2, The word their in the passage refers toA．brakes.B．skis.C．ski manufacturer.”相关的问题
A．Improves efficiency.
B．Save money.
C．Improve quality.
D．Is useful.
A．Giving witnesses a selection of face shapes to choose from before facial features are added.
B．Generating facial features after several rounds of selections.
C．Combining the images generated by different witnesses or even from a single witness.
D．Generating three-quarter angle views of the face.
Vitamins, which come in many different types all of which are quite diverse in chemical configuration and function, can be any of several organic substances that are separated into water-soluble and fat-soluble groups. Originally defined as organic compounds obtainable in a normal diet and capable of maintaining life and promoting growth, vitamins are differrent from carbohydrates, fats, and proteins in function, as well as in the quantities in which organisms require them. So critical are vitamins to a body's essential strength and health that if they are absent from the diet or not properly absorbed by an organism, a specific deficiency disease may develop.
The term vitamin originated from "vitamine," a word first used in the early 19th century to designate a group of compounds considered vital for life (though the term "accessory food factor" sometimes is used interchangeably to refer to these substances). Like other nutrients, vitamin consumption is imperative to keep our bodies functioning properly, and if there is a lack of vitamin consumption, the body will fail to react in a way that's considered healthy. Lack of vitamin A will result in various disorders that most commonly involve the eye and the tissues around it. One of the earliest symptoms of vitamin A deficiency is nyctalopia, the medical term for night blindness, which causes a visual failure to adapt quickly from light to darkness and an inability to see in the dark. This aspect of vision is normally dependent on rhodopsin, a protein found in the eye that maintains itself only in the presence of vitamin A; in the lack of vitamin A, rhodopsin will malfunction.
These earlier symptoms are quite harmless but the side effects can become increasingly serious if not treated early on. If the deficiency is severe and persists, especially in malnourished infants and children, a condition known as xerophthalmia--when the eyes are sensitive to light, the secretion of lubricating tears is stopped, and the eyelids become swollen and develop pus -- may develop. Furthermore, the mucous surfaces of the eye may become eroded, allowing infection to set in, thus leading to ulceration and other destructive changes of the cornea and other structures of the eye, resulting eventually in blindness.
A Early signs of vitamin A deficiency may also be reflected in changes in the membranes of the mouth, throat, and respiratory and genito-urinary passages where the lining membranes become malnourished and dry and lose their cilia, the tiny hairlike projections that normally help in clearing away foreign particles. B The natural immune system is weakened and if insufficient intake of vitamin A is prolonged, the skin may become dry and rough. C Vitamin A deficiency may also result in defective bone and teeth formation and in poor general growth.D
However, an excessive intake of vitamin A can also cause severe damages to the body causing a symptom called "hypervitaminosis A", which happens when a person takes in more than 150 milligrams of vitamin A over a long period of time; the vitamins are stored in the liver and can reach dangerous level because the A vitamins are not employed to make the bodies stronger, but rather, stored as toxic material. Excessive amounts of vitamin A can cause nausea, dryness of skin, blurred vision, drowsiness, and bone pain.
Vitamin A can be found in all animal livers, in milk products, and in many yellow and green leafy vegetables which contain carotenes, chemically related substances that are converted to vitamin A in the body. There are various other vitamins that the human body needs in order to survive; the excessive intake of vitamin A, or the lack of intake of other vitamins, causes detriment to the human body--at all times, moderation is key.
According to the paragraph 2, which of the following is true of vitamins？
A．Our body's operation is dependent on vitamins, which means that the body would not function without vitamins.
B．The term "vitamin" was first used in the 19th century, and until then, they were known as the "accessory food factor".
C．Insufficient consumption of vitamins may cause out body to stop functioning properly.
D．Lack of vitamin causes night blindness as well as many disorders that involve the eye and organs related to it.
A．The adeptness to see clearly without depending on proteins.
B．The aptitude to rapidly adjust to the changes in the amount of light.
C．The ability to see clearly in complete darkness.
D．The competence to rapidly adjust from natural light to artificial light.
A．Square Ａ.
B．Square Ｂ.
C．Square Ｃ.
D．Square Ｄ.
A．Hoover was criticized and blamed for laws that he had to sign, because there was no other choice.
B．Tightening of the money supply may have been considered a befitting strategy if the circumstances were different.
C．Raising taxes and tariffs should have brought America out of the depression according to theories.
D．Modem economists view president Hoover as a victim, who was forced to make mistakes.
A．incompetence.
B．officials.
C．policies.
D．ineffectiveness.
A．To find out if the student can return at a later time.
B．To express that she is in the middle of something.
C．To indicate that she has time to talk with the student.
D．To discourage the student from staying for too long.
A．Boundaries where two pieces of the Earth's outer shell diverge.
B．Zones where one tectonic plate moves under another.
C．The expansion of oceans and other bodies of water.
D．The existence of a land bridge that connected continents.
A．The causes of a housing market crash
B．An exception to a national economic trend
C．The city's attempts to attract businesses
D．The progress of a local economic recovery
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