--- I saw your uncle take a taxi to the airport. Why didn’t you drive him there?

--- I ______. But my car ______.

A．would; was fixed

B．would have; was fixed

C．would have; was being fixed

D．did; was being fixed

什么叫自蔓延高温合成？简述自蔓延高温合成法的主要应用工艺。