fast能当形容词嘛？

fast既是形容词又是副词的形式。作形容词时可用作定语，也可作表语。如：He
is
fast.(表语)There
are
many
fast
resterrants
in
the
city.(定语)用作副词时作状语。如：He
is
running
very
fast.=He
is
very
fast.