I play basketball with my friend. 这个句子I不加be，

Posted 2023-03-17

为什么They were singing while we were dancing.要加be

参考技术A （1）I
play
basketball
with
my
friend.
（一般现在时态）
（2）They
were
singing
while
we
were
dancing.（过去进行时态）
一般现在时的句子结构
1、当句子表状态说明主语是什么或怎么样时,其句型：主+BE动词（am,is,are）+表语,否定式是在BE动词后加not,疑问句是将BE动词提前到句首（即在主语之前）
e.g.The
twin
sisters
are
from
America.这对孪生姐妹是美国人.
The
twin
sisters
are
not
from
America.
Are
the
twins
from
America?
2、当谓语由实义动词充当,主语不是第三人称单数时,
句子结构为：主语+动词原形+其它
否定式为：主语+don't+动词原形+其它
疑问句为：Do+主语+动词原形+其它?
e.g.We
speak
Chinese.
Do
you
speak
Chinese?
They
don't
speak
Chinese.
当主语是第三人称单数时：
句子结构为
主语+动词（词尾加s或es）+其它.
否定式为：主语+doesn't+动词原形+其它.
疑问句式：Does+主语+动词原形+其它?
过去进行时：

概念：表示过去某段时间或某一时刻正在发生或进行的行为或动作。

例：We
were
copying
the
new
words
this
time
yesterday.
时间状语：at
this
time
yesterday,
at
that
time或以when引导的谓语动词是一般过去时的时间状语等。

基本结构：was
/
were
+doing

否定形式：was
/
were
+
not
+
doing.

一般疑问句：把was或were放于句首。

过去进行时的用法

1）过去进行时表示过去某一时刻，某一阶段正进行的动作，由“was
(were)+现在分词”构成。例如：
In
1980
he
was
studying
in
a
university.
He
was
reading
a
novel
when
I
came
in.
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