She hums a tune while cooking dinner.

她在做晚饭时哼唱了一首曲子。

She hums along with the radio while driving.

她开车时跟着收音机哼唱。

Customers in each car she's tidying don't seem to mind that she hums as she works.

她常常一边工作一边轻轻哼唱，车内的乘客似乎并不太在意。