do double dutyUSE somethingto do more than one job or be useful for more than one thing at the same time 做两份工作;有双重作用,可以两用do double duty as The sofa does double duty as a guest bed. 这张沙发还可以在有客人时当床用。
do double duty• Choose a sofa that will do double duty as a guest bed.
→ do double duty at double duty(1)