A system or action whereby something happens is one that makes that thing happen.
by which
The company operates an arrangement whereby employees may select any 8-hour period between 6 am to 8 pm to go to work.
该公司做出了一种安排,据此员工可以在上午6点到晚上8点之间任意选择8个小时去上班。
the system whereby Britons choose their family doctors and the government pays those doctors.
英国人自选家庭医生并由政府付费的制度。
a method of soil conservation whereby ploughing is undertaken along contours rather than with the slope.
一种沿等高线而不随斜坡犁耕的水土保持方法。