【答案解析】[解析] 题意：都快5点钟了，该下班了。
划线词quit意为“停止”。
A项increase意为“增加”。例：The workers are trying their best to increase productivity.工人们正竭尽全力提高生产力。
B项stop意为“停止”。例：The train stopped at the station.火车在车站停了下来。
C项continue意为“继续”。例：He continued his writing for another year.他又继续写了一年。
D项keep意为“保持，阻止”。例：Robbie couldn"t keep the child from yelling.罗比没法使孩子不大叫大嚷。故选B。