单选题 During a period of protracted illness, the sick can become infirm, ______ both the strength to work and many of the specific skills they once possessed.

【正确答案】 D
【答案解析】(lose失去)。句意为：身患痼疾，病人的身体就会虚弱，既丧失工作能力又失去许多已有的特殊技能。A．regain恢复；C．deny否认；D．pursue追求。