should在这里的用法Some festivals are held to honour the dead or to

should在这里的用法
Some festivals are held to honour the dead or to satisfy the ancestors,who might return either to help or to do harm.For the japanese festival Obon,people should go to clean graves and light incense in memory of their ancestors.
后一句中的should是什么意思呢?“应该”?觉得有点别扭.