His lecture was difficult and I didn’t know ________ he said meant in his lecture．

A.that

B.what

C.that that

D.what what

答案及解析： D

解析：

第一个what作动词meant的宾语，第二个what作动词said的宾语，即在I didn’t know what what he said meant in his lecture中，I didn’t know为主句，what what he said meant in his lecture为宾语从句，而在此宾语从句中又包括有what he said这样一个主语从句。