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in the early days of sea travel, seamen on long voyages lived exclusively
on salted meat and biscuits. many of them died of scurvy (坏血病), a disease of the
blood which causes swollen gums, livid white spots on the flesh and general
exhaustion. on one occasion, in 1535, an english ship arrived in newfoundland
with its crew desperately ill. the men′s lives were saved by iroquois indians
who gave them vegetable leaves to eat. gradually it came to be realized that
scurvy was caused by some lack in the sailors′ diet and captain cook, on his
long voyages of discovery to australia and new zealand, established the fact
that scurvy could be warded off by the provision of fresh fruit for the
sailors.
nowadays it is understood that a diet which contains nothing harmful may
yet result in serious disease if certain important elements are missing. these
elements are called “vitamins”. quite a number of such substances are known and
they are given letters to identify them, a, b, c, d, and so on. different
diseases are associated with deficiencies of particular vitamins. even a slight
lack of vitamin c, for example, the vitamin most plentiful in fresh fruit and
vegetables, is thought to increase significantly our susceptibility (敏感度) to
colds and influenza.
the vitamins necessary for a healthy body are normally supplied by a good
mixed diet, including a variety of fruit and green vegetables. it is only when
people try to live on a very restricted diet, say during extended periods of
religious fasting (斋戒), or when trying to lose weight, that it is necessary to
make special provision to supply the missing vitamins.
1. scurvy is a disease that is provoked by ____
A. salted meat and biscuits B. exhaustion
C. want of some essential substances D. lack of fresh vegetables and
fruits
2. in the last sentence of paragraph 1, “warded off” could probably be
replaced by ____.
A. got rid of B. killed C. avoided D. cleared away
3. to avoid such disease as scurvy, it′ s better for us ____.
A. not to eat much salted meatb. B. to supplement our diet with various
vitamin pills
C. to have more fresh fruit and vegetablesd. D.to develop a good dietary
habit
4. based on the passage we can safely conclude that if our diet is not
comprehensive enough ____.
A. vitamin pills are of no avail B. nutritious food might be unhealthy
C. vegetable leaves can be a good remedy D. religious fasting may help out
a lot
5. which of the following sentences best expresses the central ideal of the
passage?
A. deficiencies of vitamin c may cause serious diseases.
B. fresh fruit and green vegetables contain enough nutrition that is
necessary for a healthy body.
C. vitamins play a vitally important role in people′ s health.
D. a good mixed diet normally supplies sufficient vitamins for us.
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发表于 2017-8-6 20:46:15