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