短語詞組短語wave field upward continuation 波場上延Potential field downward continuation 位場曏下延拓potential field upward continuation 位場曏上延拓wave field downward continuation 波場延拓wave -field continuation 波場延拓potential field continuation 位場延拓magnetic field continuation 磁場延拓wave field continuation 波場延拓 返回 field continuation