During the depression, I used to hop freights at least once a month.在大萧条时期，我一个月至少一次要偷偷扒搭货运列车。Exfoliate your back at least once a week.每周至少一次搓掉背部死皮。Muslims are expected to make at least one pilgrimage to Mecca, Muhammad's birthplace.穆斯林应该去穆罕默德的出生地麦加朝圣至少一次。