单选题 Please be advised that every night shift worker is eligible for free parking ______ on duty.
  • A. during
  • B. after
  • C. while
  • D. still
【正确答案】 C
【答案解析】[解析] 语法：连词 1．选项由连词和介词构成。 2．连词while后直接接从句，从句中“主语+动词”(every night shift is)这一部分被省略。因此C为正确选项。