大全section1-7

7.Even today, a century after P developed the first vaccine,rabies almost always kills its victims unless inoculated in the earlist stage of the disease.

B. its victims unless they are inoculated

C. its victims unless inoculation is done

the key answer is B.but i have no idea what "they" refers to, the vaccine or the victims? And it seems to me that C is a better answer.

they refers to the victims.

B、总是杀死感染者除非他们接种疫苗，

C、总是杀死感染者除非疫苗被接种，

你觉得哪个好呢？

logical predication