A strict vegetarian is a person who never in his life eats anything derived from animals. (46)The main objection to vegetarianis

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问题     A strict vegetarian is a person who never in his life eats anything derived from animals. (46)The main objection to vegetarianism on a long-term basis is the difficulty of getting enough protein, the body-building element in food. If you have ever been without meat or other animal foods for some days or weeks(say, for religious reasons) you will have noticed that you tend to get physically rather weak. Proteins are built up from approximately twenty food elements called ’ amino-acids’, which are found more abundantly in animal protein than in vegetable protein. This means you have to eat a great deal more vegetable than animal food in order to get enough of these amino-acids. (47)A great deal of the vegetable food goes to waste in this process and from the physiological point of view there is not much to be said in favor of life-long vegetarianism.
    The economic side of the question, though, must be considered. Vegetable food is much cheaper than animal food. (48)However, since only a small proportion of the vegetable protein is useful for body-building purposes, a consistent vegetarian, if he is to gain the necessary 70 grams of protein a day, has to consume a greater bulk of food than his digestive organs can comfortably deal with.
    (49)Whether or not vegetarianism should be advocated for adults, it is definitely unsatisfactory for growing children, who need more protein than they can get from vegetable sources. A lacto-vegetarian diet, which includes milk and milk products such as cheese, can, how ever, be satisfactory as long as enough milk and milk products are consumed.
    Meat and cheese are the best sources of usable animal protein and next come milk, fish and eggs.
    Slow and careful cooking of meat makes it more digestible and assists in the breaking down of the protein content by the body. When cooking vegetables, however, the vitamins, and in particular the water-soluble vitamin C, should not be lost through over-cooking. With fruit, vitamin loss is negligible, because the cooking water is normally eaten along with the fruit, and acids in the fruit help to hold in the vitamin C.
    Most nutrition experts today Would recommend a balanced diet containing elements of all foods, largely because of our need for sufficient vitamins. (50)Vitamins were first called accessory food factors since it was discovered in 1906 that most foods contain, besides carbohydrates(碳水化合物), fats, minerals and water, these other substances necessary for health. The most common deficiencies in Western diets today are those of vitamins. The answer is variety in food. A well-balanced diet having sufficient amounts of milk, fruit, vegetables, eggs and meat, fish or fowl (i.e.) any good protein source usually provides adequate minimum daily requirements of all the vitamins.


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答案然而,因为只有一小部分蔬菜蛋白质能起到强身健体作用,若想摄取每天所必须的70克蛋白质,一个长期素食的人要消化的食物总量就得远远超出他的消化器官所能承受的限度。

解析 本句的主句是a consistent vegetarian has to consume a greater bulk of food,句中有两个从句分别以since和if引导,另有一个比较级结构。采用顺序法,按原句结构拆开。his digestive organs can comfortable deal with可理解为"他的消化器官所能承受(的限度)"。
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