be动词后面的动词形式有三种可能:
①-ing:
现在进行时,I'm
trying
to
give
you
the
right
answer.
②-ed:
被动语态,I'm
told
that
you
don't
know
her.
③-to
do:
1、表示按计划或安排要做的事.例如:They
said
goodbye,little
knowing
that
they
were
never
to
meet
again.他们告了别,不知道以后再也不会见面了。
2.表示“应该”,相当于should,ought
to.例如:You
are
to
report
to
the
police.你应该报警。
3.表示“必须”,相当于must,have
to.例如:The
letter
is
to
be
handed
to
him
in
person.这封信必须亲手交给他。
4.表示“想,打算”,相当于intend,want.例如:If
we
are
to
be
there
before
ten,we’ll
have
to
go
now.如果我们要在十点前到,我们现在就得走。