根据短文内容，从短文后的选项中选出能填入空白处的最佳选项，选项中有两项为多余选项。People, like all living things, need food. Food gives us the nutrients our bodies need.【小题1】    .Energy is needed to carry out the life processes.Our bodies cannot use the nutrients or energy in food unless the food is changed. The changing of food into a form the body can use is called digestion.What does digestion do? 【小题2】 Digestion also changes the chemicals of food. It changes large, complex food molecules（微粒）into smaller, simpler ones.【小题3】Digestion takes place in the digestive tract. The digestive tract is a long, winding tube in your body. If stretched out, the digestive tract would be more than 9 meters (30 feet) long.What are the parts of the digestive tract? The parts of the digestive tract are: the mouth, the food pipe , the stomach, the small intestine（肠）,and the large intestine.There are many organs along the digestive tracts, such as the liver. 【小题4】The digestive tract and the other digestive organs make up your digestive system.Food enters the body through the mouth. Waste materials (undigested food) leave the body through the anus（肛门）．The anus is at the end of the large intestine.Digestion is a step-by-step process.【小题5】 It takes food from one to two days to pass through the entire digestive tract.

A．It also gives us energy. B．It does not take place quickly. C．Where does digestion take place? D．Does the food also give us much strength? E．Digestion breaks down large pieces of food into smaller pieces. F．These organs are not part of the digestive tract, but they help in digestion. G．Although they don't belong to the digestive tract, they help us fight diseases.