问题补充：
According to the report, an Iranian nuclear scientist was killed and two people were injured when a bomb to a car exploded in its capital city.
A. attaching
B. attached
C. to be attached
D. having attached
答案：
A. attaching
(答案→)B. attached
C. to be attached
D. having attached
解析：句意：据报道当车上装有炸弹的汽车在首都爆炸时，一位伊朗的核武器专家被炸死，有两人受伤。这里bomb与attach之间是被动关系，attached to a car是过去分词短语作定语修饰前面的名词bomb.故选B。
