新买的菜刀,表面有一层油,怎么去除?

买来的新菜刀有一层防锈的机油。使用前用法罚瘁核诓姑搭太但咖热水把菜刀冲一遍，趁热用洗涤灵涂抹均匀，再用钢丝球擦一遍，温水冲洗干净基本就没机油味了。如果有锈痕，用钢丝球沾洗衣粉或去污粉先清洗一遍（除去铁锈），再用洗涤灵清洗一遍即可。用过的菜刀要及时除去沾染的酸、碱、盐及食物残渣，用抹布擦干保管好，下次使用时才能得心应手。切记操作时注意安全！

买来的新菜刀有一层防锈的机油。使用前用热水把菜刀冲一遍，趁热用洗涤灵涂抹均匀，再用钢丝球擦一遍，温水冲洗干净基本就没机油味了。如果有锈痕，用钢丝球沾洗衣粉或去污粉先清洗一遍（除去铁锈），再用洗涤灵清洗一遍即可。

bn=an+3
这步是令bn=an+3,bn是为了解题方便设的
因为bn=an+3
b1=a1+3=4
所以b(n+1)=a(n+1)+3
又a(n+1)+3=2(an+3)
故b(n+1)=2bn
b(n+1)/bn=2
故{bn}是首项为4，公比为2的等比数列
算出bn=2^(n+1)
an=bn-3=2^(n+1)-3

how
to
learn
english
well
english
is
one
of
the
most
important
subjects
in
middle
school.
almost
everyone
knows
that
we
should
learn
english
well,
but
few
of
us
know
how
to
learn
it
well.
karl
marx
has
set
a
good
example
for
us.
he
once
said,
"when
one
is
learning
a
foreign
language,
he
must
use
the
foreign
language."
in
this
way,
he
could
use
several
languages.
a
saying
goes,
"practice
makes
perfect."
when
we
learn
english,
we
should
read
more,
speak
more,
listen
to
english
from
time
to
time
and
practise
writing
every
day.
don't
be
afraid
of
making
mistakes.
only
in
this
way
can
we
learn
it
well.
(如果这些字数不够的话,那你看看下篇:
learning
english
requires
action.
you
may
know
all
the
learning
tips,
but
if
you
don't
start
doing
things,
you
will
achieve
nothing.
the
fact
is,
if
you
want
to
learn
to
speak
english
well,
you
must
change
your
life.
here
are
some
examples
of
things
you
will
have
to
do:
1.
read
a
book
in
english
for
an
hour
every
day,
analyzing
the
grammar
in
sentences
and
looking
up
words
in
an
english
dictionary
2.
listen
to
an
audio
book
or
other
recording
in
english,
stopping
it
frequently,
trying
to
understand
what
is
being
said,
and
trying
to
imitate
the
speaker's
pronunciation
3.
spend
your
afternoon
practicing
the
pronunciation
of
the
english
"r"
sound
4.
carefully
write
an
e-mail
message
in
english,
using
a
dictionary
or
a
web
search
every
20
seconds
to
make
sure
every
word
is
correct,
and
taking
5
minutes
to
write
one
sentence
5.
think
about
an
english
sentence
you've
read,
wondering
if
it
could
say
"a"
instead
of
"the"
in
the
sentence,
and
trying
to
find
similar
sentences
on
the
web
to
find
out
the
answer
6.
walk
down
the
street
and
build
simple
english
sentences
in
your
head
(talking
to
yourself
in
english
about
the
things
you
see
around
you)
what
kind
of
person
would
do
all
these
crazy
things?
only
one
kind。the
kind
of
person
who
enjoys
doing
them。
if
you
want
to
learn
to
speak
english
well,
you're
going
to
have
to
become
that
person.
you
cannot
hate
doing
these
things.
have
you
ever
heard
of
a
person
who
became
successful
by
doing
something
he
hated?
the
problem
with
learning
and
teaching
english
as
a
foreign
language
is
that
all
english
learners
want
to
speak
english
well;
however,
most
learners
don't
want
to
spend
time
on
learning
english
on
their
own.
(which
is
probably
why
they
sign
up
for
english
classes
and
hope
their
teacher
will
force
knowledge
into
their
heads?)
this
lack
of
motivation
means
that
learners
basically
don't
spend
their
own
time
on
learning
english,
and
if
they
do,
they
don't
do
it
regularly.
for
example,
a
typical
learner
might
study
english
phrasal
verbs
for
12
hours
before
an
english
exam.
however,
he
will
not
read
a
book
in
english
for
30
minutes
every
day.
he
just
doesn't
feel
that
learning
english
is
pleasant
enough,
so
he
will
only
do
it
if
he
has
to.
the
problem
is
that
a
huge
one-time
effort
gives
you
nothing,
while
small,
everyday
activities
will
give
you
a
lot.
if
you
are
one
of
those
learners
and
don't
feel
like
practicing
the
pronunciation
of
the
"r"
sound
or
thinking
about
english
sentences
every
day,
we
have
news
for
you:
you're
going
to
have
to
make
yourself
want
to
do
these
things.
in
other
words,
you'll
have
to
work
on
your
motivation.
fortunately,
there
are
proven
techniques
to
help
you
with
that.

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