all the inventions have in common is they have succeeded. A. What; what B. That; that C.

问题补充：

all the inventions have in common is they have succeeded.

A. What; what B. That; that C. What; that D That; what

答案：

解析：考查从句连词的选择。根据句子结构可知，第一空是主语从句，作is的主语，从句中缺少have 的宾语，因此选择what，第二空是表语从句，从句中不缺少成分，选择that

句意为，这些发明的共同之处是他们都成功了