23、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．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, protein 4．0 Cal/gm, and fat 8．8 Cal/gm．Each food contains different amount of these materials, as the round pictures show．

1．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

2．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 carbohydrates, 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．

3．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