Question

现在进行时、一般现在时、一般将来时、一般过去时的 用法 动词构成 标志词

Answer 1

也就是be动词，即系动词的五种变化。

现在进行时为

i
am
doing

he、she
is
doing

they
are
doing

过去进行时

i
、he
，she
was
doing

they
were
doing