The old lady has developed a

The old lady has developed a _______ cough which cannot be cured completely in a short time.

perpetual

permanent

chronic

sustained

答案及解析：本题考查形容词辨析C选项，句意为“这个老妇人患了慢性咳嗽，短期不可能痊愈”，chronic“长期的，慢性的”。chronic disease专指“慢性病”，综上，C选项正确。A选项，perpetual“永远的，永恒的”，故排除。B选项，permanent“永久的，持久的”，故排除。D选项，sustained“持续的”，故排除。故正确答案为C项。