Youshouldbe_______and have a senseof responsibility.
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Sammy is introvertin nature while her sister seems _____.
The expert was called upon to give an _________ speech for ten minutes.
棘皮动物的高等特征是
A. 五辐射对称体制
B. 具有活的内骨骼
C. 后口
D. 真体腔发达
棘皮动物的真体腔主要存在于
A. 围血系统
B. 水管系统
C. 围脏系统
D. 腕足系统
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