A. The importance of zooplankton in the marine food chain
B. The interdependence of two types of tiny marine organisms
C. A physical feature of zooplankton that makes them well adapted for swimming
D. A phenomenon observed in some species of zooplankton
我的笔记 编辑笔记
题型分类：内容主旨题
题干分析：教授讨论对主旨。
原文定位：
For over a century now, researchers have been trying to solve a mystery aboutzooplankton. You see, some species of zooplankton migrate, er, n-n-not the way birds do when the seasons change, but daily, in a phenomenon we call diel vertical migration, or DVM.
选项分析：教授从whale引入Plankton,明确讨论主题：zooplankton,继而在定位句明确关于zooplankton的特定DVM迁徙现象，后文给出针对该现象的几个解释。D选项最准确。
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