age-based maintenanceforcing periodic maintenanceperiodical maintenanceroutine maintenancetop of file定期: fix a date regular; at regul ...维护: safeguard; defend; uphold; k ...不定期维护: unscheduled maintenance定期维护时间: time scheduled maintenance; time,scheduled maintenance汽车定期维护: vehicle periodic maintenance下载手机词典可随时随地查词查翻译