by the day 
按日
- They let out horses by the day.
他们按天计算出租马匹。 - He hired a bicycle by the day.
他按日租用自行车。 - Day by day the king gave Jehoiachin a regular allowance as long as he lived.
30 王赐他所需用的食物,日日赐他一分,终身都是这样。
by the day[ adv ]
one every day
<adv.all>
we'll save 100 man-hours per diem