It is said that he had given up drinking.（误）

过去完成时的实质是“过去的过去”，是两个发生在过去的动作根据先后比出来的时态。改正办法：

1. It is said that he gave up drinking.（正）

2. It is said that he has given up drinking.（正）

3. It was said that he had given up drinking. （正）