Renewable resources refer to natural resources that can maintain or increase their reserves at a certain growth rate through natural forces, such as solar energy, atmosphere, water, etc. , and the amount consumed by contemporary people will not reduce the amount consumed by future generations. Species such as wild animals and plants are basically stable without human damage. Based on the above definition, Which of the following statements are true:. ['Wind blows green grasslands, and grasslands are renewable resources.', 'Coal is formed by solar energy conversion. It is therefore a renewable resource.', 'Many metal machines can be recycled after they are scrapped, so they are renewable resources.', 'Freshwater resources on the earth are very scarce and belong to non-renewable resources.']