(2) Recipe: steamed bread, braised beef and fried rape; Steamed bread is rich in sugar, and braised beef is rich in protein, so the answer is: steamed bread, braised beef, fried rapeseed; Steamed bread; Braised beef;
(3) Adding iron to soy sauce can prevent iron deficiency anemia. Baking soda reacts with acid to produce gas, and acetic acid is acidic, so the answer is: iron; Vinegar;
(4) Covering grease can prevent contact with oxygen; Band-aid can treat small wounds, so the answer is: cover with oil, band-aid.