at
a
time
意为“每次;一次”。at
one
time
意为“同时;曾经一度”,常用于过去时。at
the
time
意为“在那时;在那段时间”。常用于过去时态。例如:
1.take
two
pills
at
a
time.
一次服两粒。
2.at
one
time
they
were
friends,
but
they
are
seldom
together
now.
他们曾经是朋友,但是现在很少在一起了。
3.he
agreed
at
the
time
but
later
changed
his
mind.
他当时同意了,但后来又改变了主意。
希望能帮到你。
A.at
a
time
依次,逐一,每次.如;1.Don't
try
to
do
everything
at
once,take
it
a
bit
at
a
time.不要什么事情都一块干,要一次做一点.2.Take
the
pills
two
at
a
time.每次服2粒.
B.at
one
time一度,从前.如:At
one
time
I
used
to
go
skiing
every
winter.我有一度每到冬天就去滑雪.