“2020年托福考试阅读理解模拟练习题及答案

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2019

< br>年托福考试阅读理解模拟练习题及答案

Hormones in the Body

Up to the beginning of the twentieth century,the nervous

system was thought to control all communication within the

body and the resulting integration of ists had

determined that nerves ran,essentially,on electrical

impulses were thought to be the engine for

thought,emotion,movement,and internal processes such as

r,experiments by William Bayliss and Ernest

Starling on the chemical secretin,which is produced in the

small intestine when food enters the stomach,eventually

challenged that the small intestine,secretin

travels through the bloodstream to the ,it

stimulates the release of digestive this

fashion,the intestinal cells that produce secretin ultimately

regulate the production of different chemicals in a different

organ,the pancreas.

Such a coordination of processes had been thought to

require control by the nervous system;Bayliss and Starling

showed that it could occur through chemicals

discovery spurred Starling to coin the term hormone to refer

to secretin,taking it from the Greek word hormon,meaning“to

excite”or“to set in motion.”A hormone is a chemical

produced by one tissue to make things happen elsewhere.

As more hormones were discovered,they were

categorized,primarily according to the process by which they

operated on the glands(which make up the endocrine

system)secrete hormones directly into the

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glands include the thyroid and the exocrine

system consists of organs and glands that produce substances

that are used outside the bloodstream,primarily for

pancreas is one such organ,although it secretes

some chemicals into the blood and thus is also part of the

endocrine system.

Much has been learned about hormones since their

play such key roles in regulating bodily

processes or behavior that their absence would cause

immediate most abundant hormones have effects that

are less obviously urgent but can be more far-reaching and

difficult to track

：

They modify moods and affect human

behavior,even some behavior we normally think of as

al systems are very minute

amounts of the right chemicals can suppress appetite,calm

aggression,and change the attitude of a parent toward a

n hormones accelerate the development of the

body,regulating growth and form;others may even define an

individual’s personality quantities and

proportions of hormones produced change with age,so

scientists have given a great deal of study to shifts in the

endocrine system over time in the hopes of alleviating

ailments associated with aging.

In fact,some hormone therapies are already very common.A

combination of estrogen and progesterone has been prescribed

for decades to women who want to reduce mood swings,sudden

changes in body temperature,and other discomforts caused by

lower natural levels of those hormones as they enter middle

as hormone replacement therapy(HRT),the treatment

was also believed to prevent weakening of the least

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one study has linked HRT with a heightened risk of heart

disease and certain types of may also increase the

likelihood that blood clots

—

dangerous because they could

travel through the bloodstream and block major blood

vessels

—

will proponents of HRT have tempered their

enthusiasm in the face of this new evidence,recommending it

only to patients whose symptoms interfere with their

abilities to live normal lives.

Human growth hormone may also be given to patients who

are secreting abnormally low amounts on their e of

the complicated effects growth hormone has on the body,such

treatments are generally restricted to children who would be

pathologically small in stature without hormone

affects not just physical size but also the digestion of food

and the aging chers and family physicians tend

to agree that it is foolhardy to dispense it in cases in

which the risks are not clearly outweighed by the benefits.

word engine in the passage is closest in meaning

to

(A)desire

(B)origin

(C)science

(D)chemical

word it in the passage refers to

(A)secretin

(B)small intestine

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(C)bloodstream

(D)pancreas

word spurred in the passage is closest in meaning

to

(A)remembered

(B)surprised

(C)invented

(D)motivated

be considered a hormone,a chemical produced in the

body must

(A)be part of the digestive process

(B)influence the operations of the nervous system

(C)affect processes in a different part of the body

(D)regulate attitudes and behavior

glands and organs mentioned in paragraph 3 are

categorized according to

(A)whether scientists understand their function

(B)how frequently they release hormones into the body

(C)whether the hormones they secrete influence the aging

process

(D)whether they secrete chemicals into the blood

Paragraph 3 is marked with an arrow[→]

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