Xiao Qun works five days a week, unless there is a legal holiday during the week. Xiao Qun worked at Daping Insurance Company for the other four days except at the Volunteer Association on Friday. There was no legal holiday last week. 
Daping Insurance Company implements the system of four working days a week.
 Xiao Qun must work at Daping Insurance Company on Monday, Tuesday, Wednesday and Thursday last week.