食物链等级体系中的高等级物种平均捕获率(而捕获正在并将持续进行)处于持续上升态势之中——按照所谓食物链等级理论，这应当意味着海洋生态系统的健康平衡发生了变化。
The average trophic level of what is being caught is rising — and this in principle should indicate improving ecosystem health.
当时，各部门根据一种通常将卫生保健置于底层的等级体系，单独无系统地开展工作。
At that time, different sectors were working in an isolated, fragmented way according to a hierarchy that usually put health near the bottom.
城市体系是一定地域范围内不同等级、不同性质的城市所组成的相互联系、相互作用的系统。
The Urban system is a system that consists of some cities and these cities are different in scale and character and interact with each other.
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