Напишите данные предложения, употребив нужную по смыслу форму глагола, данного в скобках, в Indefinite Active или Passive:
1. Many organic compounds (приготавливать) from these materials.
2. Different colouring matters (содержать) in the substances used for cosmetics.
3. The food additives made by the chemists (играть) an important part in improving nutrition.
4. About million organic compounds (описывать) during the past 150 years.
5. Complex mixtures of hydrocarbon compounds which (содержать) only carbon and hydrogen (встречаться) in very large quantities as petroleum and natural gas.
6. The three known elements (соединяться) and (образовывать) a great number of compounds.