在进行飞机易损性分析时，需要计算飞机及各部件在垂直于来袭方向的投影面积。

In aircraft vulnerability analysis, it is necessary to calculate the projection areas of the aircraft and its critical components facing against the attacked direction.

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龙卷风来袭时最安全的去处是地下室，最好位于西南角落(龙卷风通常从这个方向过来)。

Thee safest place to be when a tornado is in one's area is a basement, preferably the southwest corner (where the tornado normally comes from).

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