Explanation

The phrase "He died after he had been ill for a long time."

وہ کافی عرصہ بیمار رہنے کے بعد انتقال کر گئے۔

It uses the past perfect tense "had been" to indicate that the illness occurred before the time of his death.

This tense shows the sequence of events clearly, emphasizing that the illness was a condition leading up to his death.