The human body is a living machine , and , like all machines , it needs “fuel” (燃料) to supply it with energy . This is provided by the food we eat . But how much do we need to stay healthy ?
The energy value of food is usually measured in calories . A calorie is the amount of heat required to raise the temperature of 1 kg of water by 1℃. The number of calories people need per day is different , as the pictures show . Also , the number of calories you use at any one moment normally depends on the activity you are in . For example , you need more calories for standing than for sitting , more for running than for walking , and so on .
The energy in food is in the form of three kinds of chemical materials-carbohydrate （碳水化合物）, protein（蛋白质）and fat . Carbohydrate provides 3.8 Cal/gm , protein4.0 Cal/gm , and fat 8.8 Cal/gm . Each food contains different amount of these materials , as the round pictures show .

 
56．The amount of calories supplied by equal amounts of milk , rice , and peanuts is the largest in the case of          .
A．milk        B．rice C．peanuts    D．rice or peanuts
57．Choose one statement from among A-D that agrees with the passage and the pictures above .
A．You need more calories for swimming than for mountain climbing .
B．Food contains energy in the form of carbohydres , proteins and fuel .
C．Different people need different amounts of energy depending on their age , sex and the activities they are in .
D．3 grams of milk provides 16.6 calories because carbohydrate provides 3.8 Cal/gm , protein 4.0 Cal/gm and fat 8.8 Cal/gm .
58．This article mainly tells us         .
A．all the energy is in food
B．the human body needs energy
C．the number of calories depends on your activity
D．we must only eat peanuts to get calories