The medium refers to a nutrient matrix prepared by the combination of different nutrients for the growth and reproduction of microorganisms, plants or animals (or tissues), and generally contains carbohydrates, nitrogen-containing substances, inorganic salts, vitamins, water, and other substances. Natural The medium is a medium made from animals, plants or microorganisms, including their extracts; the synthetic medium is a medium that is artificially designed based on the components of the natural medium and simulated by chemical substances; the semi-combined medium is based on The chemical reagent is mainly formulated, and a medium with a small number of natural ingredients is also added. According to the above definitions, Which of the following are semi-combined media:. ['In order to study the growth of chicken embryo cells, a medium made by adding a small amount of corn juice to a certain proportion of saline amino acid solution.', 'To promote the growth of lactic acid bacteria, a medium made from wheat wort.', 'In order to accelerate the growth of chlorophyll, the medium made of organic components, mineral elements, agar, etc. in a ratio of 3: 1: 2.', 'To observe the production of Clostridium perfringens, add 10 ml of ferrous sulfate to 1000 ml of fresh milk.']