10. вместо пропусков вставьте необходимые по смыслу модальные глаголы «can», «must», «should». 1. сhemicals be used carefully in the laboratory. 2. you stay out of the laboratory if your teacher is not there. 3. many of the chemicals be dangerous. 4. all chemicals be treated with care. 5. how you tell that a substance is pure? 6. dalton`s ideas about atom explain many scientific laws. 7. a substance be recognized by its properties. 8. a question that we answer is how the atoms get electrical charge.