effective heat exchange area

例句：

1. 1. The newpolicy is effective in reducing pollution.
   新政策在减少污染方面是有效的。
2. 2.The manager's advice was very effective in solving the problem.
   经理的建议非常有效地解决了这个问题。
3. 3.This method is effective in increasing productivity.
   这种方法在提高生产力方面是有效的。