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A special substance is painted on the tree to ______.
A．make a wound smooth.
B．prevent a disease from entering a wound.
C．cover a rough surface.
D．help a wound to dry.
答案
更多“A special substance is painted on the tree to ______.A．make a wound smooth.B．prevent a dis”相关的问题
第1题
According to the passage, what is ECGC？
A．A medicine made from green tea.
B．A powerful substance in green tea.
C．An additive essential to green tea.
D．A special treatment to make green tea.
第2题
A. examination of the heart, lungs and other organs
B. physical or mental
C. prevention of disease
D. careful diagnosis and special treatment
E. medical laboratories
F. radioactive substance
The three main elements of medical care are diagnosis of disease or injury, treatment of disease or injury and______.
第3题
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 probable be traced to the experiments of Bayliss and Starling on the hormone secretion. This substance is secreted from cells 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 secrete 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 from the Greek hormone, meaning "to excited 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 glands are the tear glands, the sweat glands, and the pancreas, which secretes pancreatic juice through a duct into intestine. Exocrine glands are also called duct glands, while endocrine glands are called ductless.
What is the author's main purpose in the passage？
A．To explain the specific functions of various hormones.
B．To provide general information about hormones.
C．To explain how the term "hormone" evolved.
D．To report on experiments in endocrinology.
第4题
Question 26 to 30 are based on the following passage .
Tress should only be pruned when there is a good and clear reason for doing so and , the number of such reasons is small . Pruning involves the cutting away of overgrown and unwanted branches , and the inexperienced gardener can be encouraged by the thought that more damage results from doing it unnecessarily than from the tree to grow in its own way .
First , pruning may be done to make sure that trees have a desired shape or size . The object may be to get a tree of the right height , and at the same time to help the growth of small side branches , which will thicken its appearance or give it a special shape . Secondly , pruning may be done to make the tree heavier . You may cut out diseased or dead wood , or branches that are rubbing against each other and thus cause wounds . The health of a tree may be encouraged by removing branches that are blocking up the center and so preventing the free movement of air . One result of pruning is that an open wound is left on the tree and this provides an easy entry for disease , but it is a wound that will heal . Often there is a race between the healing and the disease as to whether the tree will live or die , so that there is a period when the tree is at risk . It should be the aim of every gardener to reduce that risk of death as far as possible . It is essential to make the area , which has been pruned smooth , and clean , for healing will be slowed down by roughness . You should allow the cut surface to dry for a few hours and then paint it with one of the substances available from garden shops especially for this purpose . Pruning is usually done in winter , for then you can see the shape of the tree clearly without interference from the leaves and also it is very unlikely that the cuts you make will bleed . If this does happen , it is , of course , impossible to paint them properly .
26. Pruning should be done to _____.
A)make the tree grow taller . B) does not protect them form. the wind
C)get rid of the small branches D) make the small branches thicker .
27. Trees become unhealthy if the gardener_______
A)allows too many branches to grow in the middle
B)does not protect them from the wind
C)forces them grow too quickly
D)damages some of the small side branches.
28 . Why is a special substance painted on the tree ？
A)to make a wound smooth .
B)to prevent disease entering a wound .
C)to cover a rough surface .
D) to help a wound to dry .
29. A good gardener prunes tree ____
A) at intervals throughout the year
B) as quickly as possible
C) occasionally when necessary
D) regularly every winter
30 . What was the author’s purpose when writing this passage ？
A)to give practical instruction for pruning a tree
B)to give a gardener description of pruning
C)to explain how trees develop disease
D)to discuss different methods of pruning
第5题
A.explain the specific functions
B.provide general information about hormones
C.explain how the term "hormone" evolved
D.report on experiments in endocrinology
第6题
The basic drawing then has to be colored in, using the same method but with non-poisonous paint now replacing the ink. The average tattoo contains four or five colors, each injected with a separate instrument. How many needles are used each time will depend on the area to be covered, but it is possible to use as many as ten or twelve, giving up to 3,000 injections a minute. Filling in is a lengthier process than outlining, and, since most people find half an hour under the needles quite enough, a major tattoo can take a number of visits to complete. Every visit will leave the skin sere and stinging, and to prevent infection the area is finally treated with an antiseptic cream and covered with a dressing. After a few days it finally heals over, leaving the new tattoo clearly visible under the skin.
And there it stays, for, as those who get tattooed and then third better of it soon discover, getting rid of the tattoo is a far more difficult business than getting it. The tattooist is powerless to undo what he has done and can only refer unhappy customers to their doctors who, no matter how sympathetic, are able to offer little encouragement. Removing a tattoo, if it can be done at all, has to be by one of two methods, neither of them pleasant or even completely satisfactory, The first is by surgery and skin replacement, an operation which leaves permanent marks. The other possibility is to re-tat-too over the offending design with a special acidbased substance which absorbs the colors as it goes. This is a painful and lengthy process which, though less expensive than private surgery, is still quite costly." Tattooing is a thorn in the side of the medical profession", is the view of one Harley Street skin specialist. He receives a constant stream of enquiries about removal, but in most cases the expense and discomfort of having it done make people decide to go on living with their unwanted designs." Patients have to want it very much go to through with it ," he says. "Those who do are usually the ones who find that they are refused jobs, or cannot get advancement because their hands are decorated."
This is such a common event that responsible tattooists refuse to work on areas which cannot normally be covered up." The trouble is that most people don’t think about it until it’s too late." says one tattooist who had his own hands mooed some years ago, and freely admits to regretting it." I realize now that it looks in bad taste."
The fine needles are used ______ .
A．to make the first rough outline
B．to finish the rough outline
C．to make the approved drawing
D．to ink in the rough outline
第7题
Placebo pills usually are made of ______.
A．inactive substance
B．active drug
C．radioactive substance
D．explosive substance
第8题
The passage implies that cellulose is a very porous substance because it contains______.
A．a substance that creates pressure
B．millions of tiny holes
C．a substance that dissolves it
D．liquid medicine
第9题
New "fake fat" products appeared on store shelves in the United States recently, but not everyone is happy about it. Makers of the products, which contain a compound called olestra, say food manufacturers can now eliminate fat from certain foods. Critics, however, say the new compound can rob the body of essential vitamins and nutrients(营养物) and can also cause unpleasant side effects in some people. So it's up to consumers to decide whether the new fatfree products taste good enough to keep eating.
Chemists discovered olestra in the late 1960s, when they were searching for a fat that could be digested by infants more easily. Instead of finding the desired fat, the researchers created a fat the can't be digested at all.
Normally, special chemicals in the intestines(肠) "grab" molecules of regular fat and break them down so they can be used by the body. A molecule of regular fat is made up of three molecules of substances called fatty acids.
The fatty acids are absorbed by the intestines and bring with them the essential vitamins A, D, E, and K. When fat molecules are present in the intestines with any of those vitamins, the vitamins attach to the molecules and are carried into the bloodstream.
Olestra, which is made from six to eight molecules of fatty acids, is too large for the intestines to absorb. It just slides through the intestines without being broken down. Manufacturers say it's that ability to slide unchanged through the intestines that makes olestra so valuable as a fat substitute. It provides consumers with the taste of regular fat without any bad effects on the body. But critics say olestra can prevent vitamins A, D, E, and K from being absorbed. It can also prevent the absorption of carotenoids(类胡萝卜素), compounds that may reduce the risk of cancer, heart disease, etc.
Manufacturers are adding vitamins A, D, E, and K as well as carotenoids to their products now. Even so, some nutritionists are still concerned that people might eat unlimited amounts of food made with the fat substitute without worrying about how many calories they are consuming.
Olestra is a substance that makes foods 'fat-free while keeping them delicious.
A．Right
B．Wrong
C．Not mentioned
