高中名词性从句练习The old man insisted _____ the round plate _____ he

高中名词性从句练习
The old man insisted _____ the round plate _____ he saw in the sky was nothing but a UFO from the outer space.
A.what…what B.that…that C.what…that D.that…what
In her letter she wrote down her answer to the question _____ it was meaningless to discuss the salary since she had not decided to go to that company.
A.how B.what C.which D.that
As a matter of fact,we found some truth in his answer _____ he gave in his letter to Professor Brown.
A.what B.when C.whether D.which
Few people present at yesterday’s meeting agreed to his opinion _____ China has entered the Information Age.
A.which B.why C.whether D.that