Econometrics method, widely applied in every domain in economic research, possesses three basic factors: theory, methodology and data.

计量经济学方法已被广泛地应用于经济研究的各个领域，理论、方法、数据是计量经济研究的三大基本要素。

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In this paper, the nonlinear diffraction problem is studied with potential flow theory in frequency domain for three-dimensional floating body sailing in waves on deep water.

本文应用势流理论和频域方法研究了三维浮体在深水域波浪中航行时的非线性绕射问题，该问题包括非线性兴波问题和非线性绕射问题。

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There are three paradigms of the domain of the study of the effectiveness of teachers: theory of characteristics, theory of behaviour and cognition and theory of contingency.

在教师的有效性的研究领域存在三种范式 ：性格理论、行为和认知理论、权变理论。

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