问题
选择题
_____ all the inventions have in common is ______ they have succeeded.
A．What; what
B．That; what
C．What; that
D．That; that
答案
答案：C
第一空既是主语从句的(谓语have)宾语,又是主句的主语,所以应该填what；第二空用that来引导表语从句。
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