This work order must be completed by Friday;（ ）, you may have to

This work order must be completed by Friday;（ ）, you may have to work late these days.
A、unless
B、moreover
C、therefore
D、or
【正确答案】：C
【题目解析】：unless除非，如果不；moreover而且；therefore因此；or或者；根据句意这份工单必须在星期五之前完成；因此，这些天你可能要工作到很晚，故选C。