periodic造句
Long long ago, we knew the
periodic motion of a planet.
很久以前, 我们就知道行星的周期运动.
Periodic checks are taken to ensure that high standards are maintained.
定期检查以确保维持高水准。
Some commercial laboratories use
periodic nitrate tests as guides.
许多商业性的试验室已应用定期的硝态氮分析作为指导.