画组合体三视图的基本原则:先大形体后小形体、先主要形体后次要形体、先外轮廓后内细节、先圆或圆弧后直线、先可见轮廓线后不可见轮廓线。
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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