从下列单词中选择适当的词填空，每个词只能用一次。 

weight completely which advisable  certain  what  

units  exercise    if     amount   than   Living 

Meat and vegetables are measured in grams and kilograms. Milk and other liquid foods are measured in litres and millilitres. These51only measure quantity; they do not measure the value of food to the body. The unit52measures the quality or value of food is the “ calorie” . A calorie is the53of heat given off by food when it bums. The measurement tells how much energy a54food has when it is55used by the body. 

Our bodies use varying amounts of calories. The more56we take,the more calories we burn.57we eat food which contains more calories58we use up, then it is possible that we would increase in59. In order to avoid becoming overweight it is60to eat a balanced diet and not eat too many foods that have a high calorie rating.