usefulness
noun
ˈjuːsfəlnɪəs
noun
1
the
state
of
being
useful
or
the
degree
to
which
something
is
useful
有用; 实用性
[+
of
]
There
are
doubts
as
to
the
usefulness
of
this
approach
(=it
may
not
be
useful)
.
人们对这种方法是否有用有怀疑。
As
a
commuter
service,
the
ferry
has
outlived
its
usefulness
(=is
no
longer
useful)
.
作为一种通勤服务，渡船已经没有用武之地了。