Question

I don't think

I don't think he could have done such a stupid thing last night ，（）？ A do i B could he Cdid he D has he

He doesn't believe what Maria said is right ()? A is it B isn't it C does he D doesn't he

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。

Answer 3

D.第一句，我不认为他昨晚上做了一件傻事，强调的是他的行为，所以对“他”反义疑问。
C. 第二句，他不相信Maria说的是对的，强调的是他的行为，所以对“他”反义疑问。
也可以理解为固定句式，第一人称的反义疑问句是对其后的句子反义，第三人称的是对主语反义。

Answer 4

DC

Answer 5

b c

Answer 6

B，C。