In the last hundred years, traveling (become) much easier and more comfortable. In the 19th century, it (take) two or three months to cross North America by covered wagon. The trip (be) very rough and often dangerous. The situation (change) a great deal over the last century. Now you can fly from New York to Los Angeles in a matter of hours.​

became

took

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Explanation:

In the last hundred years, became much easier and more comfortable. In the 19th century, it took two or three months to cross North America by covered wagon. The trip was very rough and often dangerous. The situation changed a great deal over the last century. Now you can fly from New York to Los Angeles in a matter of hours.​

eli whitney was an american inventor best known for inventing the cotton gin. this was one of the key inventions of the industrial revolution and shaped the economy of the antebellum south.