once a week/once every three months etcREGULARone time every week etc, as a regular activity or event 每周一次/每三个月一次等 Staff meetings take place once a week. 员工会议每周举行一次。
They took separate holidays at least once every two years. 他们每两年至少有一次各自去度假。
→ once a week/once every three months etc at once1(1)