10. Заместо пропусков вставьте нужные по смыслу модальные глаголы can, must,

10. Вместо пропусков воткните нужные 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. Daltons 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.