题干
The wounded policeman ____though doctors made every effort to save him.
A：died
B：had died
C：killed
D：has been dead
答案(点此获取答案解析）
A
，为了研究X的结构，将化合物A在一定条件下水解只得到B（分子式为C8H8O3）和C（分子式为C7H6O3）．C遇FeCl3水溶液显紫色，与NaHCO3溶液反应有CO2产生． 