There are two posters in my room.
We were at home yesterday.
They didn't travel by train to Italy last year.
1. They were watching the moving particles. наблюдали (частью глагола-сказуемого)
2. The technique employed uses a single probe. задействованная, использованная, примененная, употребленная (определение)
3. When isolating radium, Marie Curie found other radioactive elements.
изолируя (обстоятельство)
4. The paper discussed concerned the problem of radioactivity. обсужденный (определение)
5. This reaction involves the following temperature changes. последующие (определение)
6. Steam is usually generated in a boiler heated by fire. воспроизводится, вырабатывается (часть глагола-сказуемого в страдательном залоге)
we were
they didn't