is是
be动词。
be动词包括：am
,
is
,
are.
如果把一个句子变成
疑问句，首先要看这个句子的动词是什么。
如果句中有be动词，直接把be动词提前。
例如：
This
is
a
pen.有be动词，直接提前，就是Is
this
a
pen?
They
are
eating
apples.
Are
they
eating
apples?
如果句中没有be动词，而是实意动词，就得借助于
助动词do
或
does
提问。
例如：
They
had
an
oral
english
class
yesterday.
had
是实意动词。借助助动词提问：
Did
they
have
an
oral
english
class
yesterday?
had
是
过去式，所以用did
提问。变为疑问句的时候动词had
要还原为have.
He
goes
to
school
by
bus
everyday.
go
是实意动词,就得借助助动词does提问。变为：Does
he
go
to
school
by
bus
everyday？
he
是第三人称单数，所以用does
提问，疑问句中goes还原为go