That's because not every single line is perfect iambic pentameter. Line after line of perfect meter ends up sounding more like a nursery rhyme than poetry, so poets (and playwrights) will play with the meter to emphasize certain words. Let's skip back to one of the non-perfect lines in the Prologue:
Hull is a town in Plymouth County, Massachusetts, United States, located on a peninsula at the southern edge of Boston Harbor. Its population was 10,293 at the 2010 census. Hull is the smallest town by land area in Plymouth County and the fourth smallest in the state.
Hull Paragon Interchange is an integrated rail and bus station in the city centre of Kingston upon Hull, England.he term Hull (Paragon) has also been used by Network Rail. Since redevelopment in 2007 the official name has been Paragon Interchange; however as of 2012 timetables continued to use Hull, except when referring to bus services.