—We didn't find the Blacks ________ the lecture.

—No one had told him about ________ a lecture the following day.

A．to attend；there to be

B．attending；there being

C．attended；there be

D．attend；there was

创新理论是由（）在20世纪上半叶提出的。

A.亚当斯密

B.乌尔比安

C.萨缪尔森

D.熊彼得