语气上might最轻,表示一种可能性,如:I
might
finish
this
work
before
Sunday.
同时,might
可以用在过去时态中,must和can只能用在现在和将来时态中,如:He
might
be
swimming
when
I
saw
him
yesterday.
而can语气介于中间,表示具备能力做某事,如:I
can
play
football
as
well
as
him.
must则语气最强,表示一定、必须,如:He
must
be
a
student,for
he
is
in
a
school
uniform.
同时might,must还可以表示退则,用于
虚拟语气,如:She
might
have
had
lunch.
虚拟语气时can则用could代替,如:He
could
have
been
killed
for
10
years.