On the weekend, Xiaogang's family of three drove to the scenic Jingniang Lake for an outing and prepared a homemade barbecue. (1) Mom prepared dried tofu, lean meat and fish.

(1) The six nutrients needed by the human body are: water, inorganic salts, vitamins, sugar, oil and protein, while the food provided in this topic is: dried tofu, lean meat, fish, milk and bread lack vitamins, which mainly exist in vegetables and fruits, so vegetables and fruits need to be supplemented, so the supplementary food is green vegetables;

(2) The purpose of choosing ethanol gasoline is to save petroleum resources (or reduce automobile exhaust pollution);

(3) There are two conditions to promote combustion: increasing the oxygen concentration, increasing the contact area between combustible materials and oxygen, and increasing the contact area between carbon and air;

(4) Hard water contains some compounds containing magnesium and calcium, which is easy to produce precipitation, so a small amount of precipitation is found, indicating that it is hard water;

(5) For an outing in mountainous areas, the best fire extinguishing method is to use local materials, and water is the most convenient fire extinguishing method;

(6) In order to protect the environment, civilized tourists should make less garbage and don't litter.

So the answer is: (1) green vegetables;

(2) Saving petroleum resources (or reducing automobile exhaust pollution);

(3) increasing the contact area between charcoal and air;

(4) hard water;

(5) dousing with water;

(6) Don't litter.