It first infects you because you breathein some of the infectious agents.
只要吸入病原体，你就会被感染。
2
For the most part, however, we breathein the aromas which surround us without being consciously aware of their importance to us.
然而，在大多数时候，我们呼吸着周围的香气，却没有意识到它们对我们的重要性。
3
When there's a fire, follow the teachers' instructions, leave the classroom quickly and use a piece of cloth to cover your mouth and nose so that you don't breathein smoke.