CEDICT
to work a shift; to be on duty; to be on call
Wiktionary
值班。清.孔尚任《桃花扇.第五齣》:「好好!今天是他当值之日。」也作「当直」。
重編國語辭典
Are you working?
Source: Tatoeba
This painting is worth a great deal of money.