______ makes mistakes must correct them....

______ surprised me most was ______ such a little boy of seven could play the violin so well.

A. That...what B. What...that

C. That...which D. What...which

I couldn’t understand _____ with me.

A. the matter was what B. what was the matter

C. what the matter was D. that was the matter

This painting is splendid, but ______ we actually need it is a different matter.

A. that B. what

C. whether D. how

All _____ made _____ possible for China to succeed in carrying on its reforms and open-door policy.

A. what happened; it B. what happened; that

C. that happened; it D. that happened; that

We don’t doubt _____ he will succeed in the research work.

A. that B. whether

C. how D. what