The purpose of this paper is to find the applying region of the t test, i. e. the necessary and sufficient conditions for a two dimension variable forms a test, which possesses at distribution.

本文的目的是研究t检验的适用范围，给出了二维随机向量构成服从t分布统计量的充要条件。

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The gate length and the dimension of the gate head can be controlled in the T-shaped gate processing, and good process controllability and high yield can be achieved.

在该T型栅工艺中栅长和栅帽的尺寸分别进行控制，实现了较好的工艺可控性和较高的工艺成品率。

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The results indicate that the change in fractal dimension is directly proportional to the surface quality, but the roughness can′t be used to describe the morphologies of film surfaces perfectly.

结果表明，分形维的大小与薄膜表面质量成正比，而表面粗糙度不能全面描述薄膜表面形貌；

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