8 Напишите предложения, употребив глагол в скобках в соответствующем времени:
1. Measurements in all scientific works (to perform) by means of various apparatuses and instruments.
2. It is known that volume of liquids (to measure) in litres.
3. The solution kept for three months in a warm place (to become) coloured and not fit.
4. When acid (to add) to the potassium chloride solution little change (to observe) in the hydrogen ion concentration.
5. The centigrade scale (to use) in most scientific works.
6. The Fahrenheit scale (to introduce) into science in the eighteenth century.
7. Alcohol (to dissolve) many synthetic and natural substances.
8. After a thorough analysis of literature and experimental findings Mendeleyev (to arrange) all the elements in a table which consisted of vertical groups and horizontal periods.
9. In France, Sweden and Germany new elements (to discover) according to Mendeleyev table.