1、定语从句用which情况：
1，非限定性定语从句
2.关系代词前有介词
3.关系代词后有
插入语如：
1、The
sun
heats
the
earth
,
which
makes
it
possible
for
plants
to
grow
.
2、The
bodies
on
which
the
forces
act
are
in
equilibrium．
3、Here
is
the
English
grammar
book
which,as
I
have
told
you
will
help
improve
your
English.
2：如果第二个问题问的这两个短语还是与定语从句有关的话，那
so后面都加形容词，that后面加句子，as后面加名词。如：The
biscuits
are
so
delicious
that
I
want
to
eat
more.
订攻斥纪俪慌筹苇船俩The
food
is
not
so
good
as
those
we
ate
in
Bill's
home.
so...as用于否定句，和as...as意思一样。后者肯定句否定句都能用。
希望能帮到您！