Let's count them:
So, it appears that there are SEVEN tubes that make up the Trombone.
The trombone's made out of brass.
the trombone was made from wood
no
Trumpet, Trombone, tuba and french horn are the four major brass instruments
Brass.
The trombone dates back to the mid-15th century.
Trombones are made of brass.
Most are made of brass.
trumpet, trombone, baritone, tuba, and french horn
Pan American made the Champion trombone. Although I have one Champion trombone whose design would seem to pre-date the Pan Am company.
Brass?
metal