1) in the last hundred years traveling (become) much easier and very 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. things ( change) a great deal in the last hundred and fifty years. 2). mark’s english ( improve, really ) isn’t it? he (watch) american television programs and (study) his grammar every day since he first arrived in san diego
