Shifts in Tense: For each of the following sentences, identify the phrase that contains an illogical shift in tense. - 1. Up until the early twentieth century, people used oil from whales for a number of purposes—for example, they use it in lamps and to make soap, leather, and cloth—so whales were an important resource.

Shifts in Tense: For each of the following sentences, identify the phrase that contains an illogical shift in tense. - 2. Before modern whaling ships were invented, hunters approach whales in small open boats and threw harpoons by hand.

Shifts in Tense: For each of the following sentences, identify the phrase that contains an illogical shift in tense. - 3. Sailors originally had to bring whales to shore to process the oil, so whaling trips have to be short.

Shifts in Tense: For each of the following sentences, identify the phrase that contains an illogical shift in tense. - 4. Then people developed methods to process whale oil on ships, and it become possible to hunt whales for as long as four years at a time.

Shifts in Tense: For each of the following sentences, identify the phrase that contains an illogical shift in tense. - 5. In the nineteenth century, petroleum begins to take the place of whale oil for lighting, but the whaling industry continued into the twentieth century due to the demand for fat to use in soap, cosmetics, margarine, and other products.