(2016·ÄϲýʮУģÄâ)

Here's an amazing fact: Of the 1.1 million firefighters in the United States£¬about 780£¬000 are volunteers.Roughly a third of the population is     1     by mostly or all£­volunteer fire departments.

Also     2 £¬perhaps.Sometimes they have to pay for their own gear (É豸)£®