(Not knew )what was wrong with him ANot knew

能否把全句打出来,就这样的确不好辨别的.
再问： His parents began to worry.But(Not knew )what was wrong with him
再答： But 前面是句号，说明这是另一个句子，句子承前省了主语 his parents; 但最好是 didn't know. not knew 还真是有点怪。 第二题选 where 是因为先行词是表示地点的名词，且拿到定语从句中后应充当状语，因为定从中的study （读书）是不及物动词。
再问： 第一题为什么选not knew 第二题为什么不选which 或that
再答： 第一题：见追问 1 回答。 第二题：which、that 在定语从句中主语或宾语，而本题中定语从句中的谓语动词是study为不及物动词，其不能带宾语，且也有主语是he. 故不能选 which 或 that.