The hunter-gatherer tribes that today live as our prehistoric human __1__
    ancestors consume primarily a vegetable diet supplementing with animal foods __2__
    An analysis of 58 societies of modern hunter-gatherers, including the Kung of southern Africa, revealed that one-half emphasize gathering plants foods, one-third concentrate on fishing, and only one-sixth are primarily hunters,
    Overall, two-thirds and more of the hunter-gatherer’s calories come from __3__
    plants. Detailed studies of the Kung by the food scientists at the University
    of London, showed that gathering is a more productive source of food
    than is hunting. An hour of hunting yields in average about 100 edible __4__
    calories, as an hour of gathering produces 240. __5__
    Plant foods provide for 60 percent to 80 percent of the Kung diet, and no __6__
    one goes hungry when the hunt fails. Interestingly, if they escape fatal infections
    or accidents, these contemporary aborigines live to old ages despite of the absence __7__
    of medical care. They experience no obesity, no middle-aged spread, little
    dental decay, no high blood pressure, no heart disease, and their blood
    cholesterol levels are very low (about half of the average American adult). __8__
    If no one is suggesting that we return to an aboriginal life style, we certainly __9__
    could use their eating habits as a model for healthier diet. __10__
    參考答案及解析:
    1. 將as 改為like
    此處的意思是“像史前人類祖先那樣生活”。
    2. 將supplementing改為supplemented
    supplemented 修飾diet，可以看作which is supplemented with animal foods的簡化形式。
    3. 將and 改為or
    4. 將in改為on
    on average 是固定用法。
    5. 將as 改為while或者whereas
    6. 刪掉for，或者將provide改為account
    此處provide 是及物動詞，后面不用介詞for
    7. 刪掉第一個of
    despite 做介詞，后面直接接名詞。
    8. 在half后加that
    that 指代前面的blood cholesterol levels，不能省略，因?yàn)檫@里是將部落成員的膽固醇含量與美國人的膽固醇含量相比較。
    9.將if改為whereas或者while
    此處意思為“盡管沒有人……,但是……”，是轉(zhuǎn)折關(guān)系。
    10.在for后面加不定冠詞a。