Прочитайте текст и определите какой из заголовков соответствует тексту To determine blood groups the...: ответ на тест 347578 - Английский язык

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To determine blood groups, there is a method of extracting a chemical from human blood which, when mixed with a sample of the blood in question will react in a particular way according to the blood group. However, to get enough of the solution a great deal of human blood is required. But fortunately, snails’ eggs, which are the size of a pinhead, contain the same chemical – in fact, the blood of five donors would be required to supply the same amount of the chemical as is found one of the snail’s eggs.