Why can science-fiction writers talk about the possible impacts of new science and technology in ways actual scientist cannot

Suppose you need to verify how correctly use commas you open ur english textbook and scan the chaper titles in which one would most likey find the information you need

Ead this excerpt from the introduction to wheels of change by sue macy. imagine a population imprisoned by their very clothing; the stiff corsets, heavy skirts, and voluminous petticoats that made it difficult to take a deep breath, let alone exercise. add to that the laws and social conventions that cemented a man's place as head of the household and holder of the purse strings. how suffocated women must have felt. and how liberated they must have been as they pedaled their wheels toward new horizons. why does the author include this excerpt?

Which verb from is used to indicate the perfect progressive tense