they use oxygen mask to breath so they die in all the smoke
The plural of fireman is firemen. If you want to use inclusive language, then you can say firefighter and firefighters.
Cambria
The personal pronoun that takes the place of the plural noun 'firefighters' is they as a subject and them as an object.example: The firefighters use this facility for training. When they damage it, a local contractor repairs it for them at no charge.
They don't have to be beige/khaki. Many departments use black, and some even use red!
firefighters use water because when water touches something it cools down
Ducks use internal lungs to breath.
water is the most practical thing to use
There is no standard collective noun for firefighters, in which case a noun that suits the situation can be used; for example a crew of firefighters, a squadron of firefighters, a team of firefighters, etc.
It's Carbon Dioxide (CO2)
To connect the two sentences, you can use the conjunction "and." The combined sentence would be: "The firefighters climbed the ladder and he smashed the window." This conjunction indicates that both actions occurred.
Crayfish use gills to breath.
The possessive form for the plural noun firefighters is firefighters'.