TEXT B

Arid region in the southwestern United States have become increasingly inviting playgrounds for the growing number of recreation seeks who vehicles such as motorcycles or powered trail bikes and indulge in hill-climbing contests or in carving new trails in the desert. But recent scientific studies show that these off-road vehicles can cause damage to desert landscapes that has long-range effects on the area's water-conserving characteristics and on the entire ecology, both plant and animal. Research by scientists in the western Mojave Desert in California revealed that compaction of the sandy arid soil resulting from the passage of just one motorcycle markedly reduced the infiltration ability of the soil and created a stream of rain runoff water that eroded the hillside surface. In addition, the researchers discovered that the soil compaction cause by the off-road vehicles often killed native plants species and resulted in the invasion of different plant species within a few years. The native perennial species required many more years before they showed signs of returning. The scientists calculated that roughly a century would be required for the infiltration capacity of the Mojave soil to be restored after being compared by vehicles.

39. According to text, what is being damaged?
A. Motorcycles.
B. The desert landscape.
C. Roads through the desert.
D. New plant species.
正确答案是

40. According to the text, what is happening to native plants in these areas?
A. They are becoming more compact.
B. They are adapting.
C. They are invading other areas.
D. They are dying.
正确答案是

TEXT C

Without regular supplies of some hormones our capacity to behave would be seriously impaired; without others we would soon die. Tiny amounts of some hormones can modify our moods and our actions, our inclination to eat or to drink, our aggressiveness or submissiveness, and our reproductive and parental behavior. And hormones do more than influence adult behavior; early in life they help to determine the development of bodily form and may even determine an individual's behavioral capacities. Later in life the changing outputs of some endocrine glands and the body's changing sensitivity to some hormones are essential aspects of the phenomena of aging.
Communication within the body and the consequent integration of behavior were considered the exclusive province of the nervous system up to the beginning of the present century. The emergence of endocrinology as a separate discipline can probably be traced to the experiments of Bayliss and Starling on the hormone secretion. This substance is secreted from cell in the intestinal walls when food enters the stomach; it travels through the bloodstream and stimulates the pancreas to liberate pancreatic juice, which aids in digestion. By showing that special cells secret chemical agents that are conveyed by the bloodstream and regulate distant target organs or tissues. Bayliss and Starling demonstrated that chemical integration can occur without participation of the nervous system.

The term "hormone" was first used with reference to secretion. Starling derived the term form the Greek hormone, meaning "to excite or set in motion." The term "endocrine" was introduced shortly thereafter. "Endocrine" is used to refer to glands that secrete products into the bloodstream. The term "endocrine" contrasts with "exocrine," which is applied to glands that secrete their products through ducts to the site of action. Examples of exocrine juice through a duct into the intestine. Exocrine glands are also called duct glands, while endocrine glands are called ductless.

41. What is the author's main purpose in the text?
A. To explain the specific functions of various hormones.
B. To provide general information of about hormones.
C. To explain how the term "hormone" evolved.
D. To report on experiments in endocrinology
正确答案是

42. Which of the following is NOT mentioned as an effect hormones?
A. Modification of behavior.
B. Sensitivity to hunger and thirst.
C. Aggressive feelings.
D. Maintenance of blood pressure.
正确答案是

43. The text supports which of the following conclusions?
A. The human body requires large amounts of most hormones.
B. Synthetic hormones can replace a person's natural supply of hormones if necessary.
C. The quantity of hormones produced and their effects on the body are related to a person's age.
D. The short child of tall parents very likely had a hormone deficiency early in life.
正确答案是

44. According to the text, another term for exocrine glands is _______.
A. duct glands
B. endocrine glands
C. ductless glands
D. intestinal glands
正确答案是