Question

I don't think

Answer 1

I
don't
think/I
think的反义疑问句，以从句为准。但是当think前边的主语是二三人称时，以think前边的主语为准。couldn‘t
have
done（否定前移了）表示对过去的否定推测，表推测时，不以情态动词为准。若后边有表过去的时间词（如last
night），则用did提问，若没有表过去的时间词，以have提问。
所以第一题选
C；
第二题选
C。
不懂追问。

Answer 2

I
don't
think
he
could
have
done
such
a
stupid
thing
last
night
，（B）？
A
do
i
B
could
he
Cdid
he
D
has
he
He
doesn't
believe
what
Maria
said
is
right
(A)?
A
is
it
B
isn't
it
C
does
he
D
doesn't
he
英语中，think,believe等引导的宾语从句，否定转移。这种复合句改为反意问句时，要和从句的主语一致。