in last hundred year, travelling a)______(become) much easir and very comfortable.in the 19th century,it(b)_____(take) two or three  months to cross north america by a covered wagon. the trip(c)_____(be) very rough and often dangerous things (d)____(change) a grea deal in the last hundred and fifty years. now you can fly fro new york to las angeles in a matter of hours. 
complete the above sentences by feeling in the correct form of verb?
plz answer it fast i am having my exam!!