periodically 考研雅思

1.The streets are periodically scavenged.

街道清理

2.Sea mammals must emerge periodically to breathe.

海生哺乳动物必须不断浮现出海面呼吸

3.The results show that the impeller flows periodically under large negative prewhirl angle.

结果表明，在较负预旋角度下，叶轮流动呈现出周；

4.In eastern China, transgression occured periodically during Eogene, and formed specially paleobio-cenosis,mineral association and rock type.

在中国东部早第三纪沉积演化过程中曾周发生过海侵,从而形成了具有海相特征岩石类型、古生物组合。

5.The time-varying and incommutable character of the coefficient matrix of periodically time-varying linear systems are the bottleneck of the design for high precision direct integration methods.

周时变线系统系数矩阵时变与不可交换是其精细积分算法设计中瓶颈。

6.As part of the program, Lown Scholars may also return to Harvard periodically for short-term stays of one week to several months to continue collaborations.

作为该项目一部分，获得奖学金学者或需返回哈佛进行一周至数月不等短访问，以继续与学院合作。

7.Halosere A plant community in a succession that starts on land periodically inundated by the sea. Haloseres include salt-and flooding-tolerant pioneer communities on mudflats and saltmarshes.

盐生演替系列：是一种在周被海水淹没陆上进行演替植物群落。它包括那些在泥滩和盐沼上生活耐盐耐淹先锋群落。