The main organs of rice are

(1) Sugar is the most important energy-supplying substance, and starch is a kind of sugar. The main component of rice is starch, which is digested in the mouth and completely digested into glucose in the small intestine.

(2) protein is first digested in the stomach, first digested by protease in the stomach, and then thoroughly digested into amino acids by enzymes in pancreatic juice and intestinal juice; Because the small intestine is very long, with folds and villi on the inner wall, the absorption area is large, and the villi wall, capillary wall and lymphatic wall of the small intestine are very thin, which is beneficial to the absorption of nutrients, so the small intestine is the main place for absorption.

(3) The largest digestive gland in human body is the liver, and the digestive juice it secretes is bile, which can emulsify fat into fat particles.

So the answer is: (1) starch (or sugar); Oral cavity (2) amino acids; ? ⑥(3) Liver; ? angry