星形细胞瘤、少突胶质细胞瘤和多形性胶质母细胞瘤好发于______；室管膜瘤好发于______；髓母细胞瘤好发于______；脑膜瘤好发于______的主要分布部位，如静脉窦；神经鞘瘤好发于______；血管母细胞瘤好发于______和______；颅咽管瘤好发于______；脊索瘤好发于______和______；转移瘤好发于______。

When should you use distress flares and rockets?（）

A.Only when there is a chance of their being seen by rescue vessels

B.At half-hour intervals

C.At one-hour intervals

D.Immediately upon abandoning the vessel