hydrogen
noun
ˈhaɪdrədʒən
noun
1
a
colourless
gas
that
is
the
lightest
of
all
gases,
forms
water
when
it
combines
with
oxygen,
and
is
used
to
produce
AMMONIA
and
other
chemicals.
It
is
a
chemical
ELEMENT:
symbol
H
氢〔一种化学元素，符号为 H〕; 氢气