Read the following paragraph and underline the topic sentences.
Pearls are gathered by men known as pearl divers. Actually, these men do not dive. They are lowered by a rope to the bottom of the sea. Pearl gatherers work in pairs, with one remaining at the surface to help the other return from his dive. An experienced pearl diver can stay down about a minute and a half and can often make as many as thirty dives in one day.
Pearls are gathered by men known as pearl divers.
