by+时间 出现用什么时态?

1、“by＋时间”与动作性强的动词连用时，主句多用于完成式。by后的时间可指现在、过去或将来时间点。
如：by
the
time
he
was
fourteen
year
sold，he
had
learned
maths
all
by
himself.
i
shall
have
finished
it
by
the
time
you
come
back.
by
the
end
of
the
match,
they
had
kicked
two
goals
and
we
had
kicked
four.
they
must
have
finished
their
work
by
this
time.
但是，上述情况中当时间为将来时，主句动作发生在从句动作之后时，主句动词可用一般时态。如：if
you're
not
better
by
then,
i'll
take
you
to
see
the
doctor.如果到那时还不好些，我就带你去看病。
can
you
finish
this
by
tomorrow?
在明天以前你能做完这件事吗？
间或有用进行式的。如：by
the
end
of
the
first
week
the
head
of
the
department
was
saying
very
nice
things
about
me.
第一周末时系主任给我多多美言了几句。
2、“by+时间”与表状态的动词连用多用于一般式。by后时间可为现在、过去或将来时。如：by
the
end
of
the
century
the
population
numbered
about
four
million.
到世纪末人口已经达到四百万左右。you
can
borrow
my
camera,
but
i
must
have
it
back
by
five
o'clock.我的照像机你可以借去用，但是五点以前一定要还我。
by
the
time
that
the
security
guards
had
realized
what
was
happening,
the
gang
were
already
inside
the
bank.
等到保卫人员明白过来发生了什么事时，那一伙强盗已经进了银行。
he
ought
to
be
here
by
this
time
/by
now.他此刻（现在）应该已经来到这里了。
如强调某状态在某时间前已经完成，也常用完成式。如：by
next
sunday
you
will
have
stayed
with
us
for
three
months.至下星期日为止，你将与我们相聚三个月了。
3、“by＋时间”与祈使句连用，用于一般式。如：please
finish
the
task
by
the
end
of
the
month.请在月底前完成这项任务。be
here
by
this
time
tomorrow.明天这个时候要到这儿。
4、如强调某状态或动作在某时间为止还要继续下去，还可用完成进行式。如：by
the
time
you
graduate,i
shall
have
been
working
here
for
five
years.
到了你毕业时，我就在此地一直工作了五年之久

如果后面的这个时间还没有到,就用一般将来时或将来完成时；
如果后面的这个时间已经过去了,就用过去完成时.
介词by在此的意思是：到……为止,在……之前.