oxygen
noun
ˈɒksɪdʒən
noun
1
a
gas
that
has
no
colour
or
smell,
is
present
in
air,
and
is
necessary
for
most
animals
and
plants
to
live.
It
is
a
chemical
ELEMENT:
symbol
O
氧，氧气〔一种化学元素，符号为 O〕