题目

在一条离体的神经纤维中段施加电刺激，使其兴奋，则 A．所产生的神经冲动向轴突末梢方向传导B．邻近的未兴奋部分表现为膜内正电、膜外负电 C．所产生的神经冲动向树突末梢方向传导  D．兴奋部位的膜外由正电变为负电，膜内由负电变为正电 答案：DThe old man feels very _________because all his children have gone abroad and his wife _________ for almost two years.A．alone, has diedB．lonely, diedC．lonely, has been deadD．alone, has been dead