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【简答题】
腔肠动物所特有的细胞 是( ) ,遍布于体表,以触手最多。
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皮皮学刷刷变学霸
举一反三
【单选题】Intra-industry trade theory
A.
explains why the United States might export autos and import clothing.
B.
explains why countries export and also import differentiated versions of the same product, such as different types of autos.
C.
assumes that transportation costs do not exist.
D.
ignores seasonal considerations.