Lacking substance or concreteness;tenuous or indefinite. 不可靠的，不具体的;细微的或模糊的收藏
To illustrate the procedure and to lend concreteness to the ideas expressed in this section, a specific boundary-value problem is studied 为了说明方法和对本节所表示的概念的具体化，将研究一个特殊的边界值问题。收藏
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