The picture shows the human digestive system. Please answer the following questions according to the pictures. (1) The largest digestive gland is _ _ _ _ _, which can secrete _ _ _ _ and promote _ _ _

The picture shows the human digestive system. Please answer the following questions according to the pictures. (1) The largest digestive gland is _ _ _ _ _, which can secrete _ _ _ _ and promote _ _ _ _. In the figure, the stomach, small intestine, liver, duodenum, pancreas, cecum, anus and appendix.

(1)③ The liver is the largest digestive gland in human body and can secrete bile. Bile does not contain digestive enzymes, but it can emulsify fat and promote fat digestion.

(2) The digestive glands located outside the digestive tract are ③ liver, ⑤ pancreas and salivary glands.

(3) The main place for digesting food and absorbing nutrition is the small intestine, which is the longest section of the digestive tract, with folds and villi on it, thus increasing the area for digesting food and absorbing nutrition; There is intestinal juice secreted by small intestinal glands in the small intestine, pancreatic juice secreted by pancreas flows into the small intestine through pancreatic duct, and bile secreted by liver flows into the small intestine through bile duct, which is beneficial to digestion of food; The villus wall, capillary wall and lymphatic capillary wall of small intestine are very thin, which is beneficial to the absorption of nutrients. Therefore, the small intestine is the main place to digest food and absorb nutrition, and its starting end is the duodenum.

So the answer is: (1)③ liver; ? Bile; Fat.

(2)③ Liver; ⑤ pancreas; ? salivary gland

(3)② Small intestine; ? Duodenum.