单选题 As no one in the small village (knew) (nothing) about medicine, Mrs. Smith, a for-mer nurse, (had to) work (as) a doctor.
A. knew B. nothing C. had to D. as

【正确答案】 B
【答案解析】改为anything。前面是否定，后面就必须用anything，用nothing就是双重否定了。