What is used to correct for both induced and permanent magnetism，and consequently must be
A. Flinders bar
B. Soft iron spheres
C. Fore-and-aft permanent magnets in their trays
D. Heeling magnet
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Pollution regulations require that each scupper in an enclosed deck area have a ______．
A. Wooden plug
B. Soft rubber plug
C. Two-piece soft patch
D. Mechanical means of closing
北大洋西部加勒比海地区东风波的坏天气通常位于。
A. 波轴及波前
B. 波轴及波后
C. 波轴附近
D. ABC都对
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