grammar exercise

can yu correct these grammar exercise ?
Mark all the verbs and verbals in the following paragraph and correct their form, tense, or mood if necessary. For centuries the natives of Melanesia, a group of islands laying northeast of , have practice an unusual religion. It began in the eighteenth century when European explorers first have visited the islands. The natives were fascinated by the rich goods or “cargo” possessed by the explorers. They saw the wealth as treasures of the gods, and cargo cults eventually had arised among them. Over the centuries some Melanesians turned to Christianity in the belief that the white man’s religion will bring them the white man’s treasures. During World War II, US soldiers, having arrived by boat and airplane to have occupied some of the islands, introduced new and even more wonderful cargo. Even today some leaders of the cargo cults insist that the airplane is worship as a vehicle of the Melanesians’ future salvation.