I think it is his pen.(改为否定句） I _______ _____it_______his pen.

题目

I think it is his pen.(改为否定句） I _______ _____it_______his pen.
最好说出理由
你们这么多人回答，可能否告诉我为什么后面的is不要改为isn’t

答案

将think否定,即I don't think it is his pen.
叫做“否定前移”,英语的固定用法