John looked unhappy when i went to see him yesterday

题目

John looked unhappy when i went to see him yesterday
John looked unhappy when i went to see him yesterday,but I didn't know what he _______(think ) about.
请回答尽可能详细,包括答案和解析,

答案

答案是【thought】
首先看横线附近这一句子,but I didn't know what he 【thought】about
这里明显know后面有一个由what疑问词引导的宾语从句,由于是过去时,所以后面直接就是过去式
【thought】
词组【think about】考虑,想
翻译：
昨天当我去看望约翰的时候,他看去来不开心,但不知道到他在想什么.
祝学业进步!