Question

and biking. no cars are allowed.
these routes were made for trains many years ago. once
the rails are removed, the paths are perfect for bicycles.
you can ride these
ail trails\ through cities and from one
city to another. the longest rail trail, in missouri, is 225
miles long!
a cyclist travels across an old railroad bridge on a rail trail.
fill in the blanks to explain why the
author thinks rail trails are good for
bikers.
rail trails are because they
let bikers avoid city streets. the trails
are built on old routes that
no longer use. so, bikers can ride for
miles without coming near

Explanation:

1. For the first blank: From the text, rail trails are good (suitable) for bikers as they avoid city streets. So a word like "good" or "ideal" fits. Given the context of being good for bikers, "good" (or a similar positive adjective; if options include "good" or "ideal", "good" is appropriate here as per the explanation about avoiding city streets making them good for bikers).
2. For the second blank: The text says "These routes were made for trains many years ago. Once the rails are removed...", so the routes were for trains, so "trains" is the correct word (the routes that trains no longer use).
3. For the third blank: The text says "No cars are allowed" and "let bikers avoid city streets", so bikers can ride without coming near "cars" (since city streets have cars, and rail trails avoid that).

Answer:

First blank: good (or ideal, depending on options; assuming standard options, "good")
Second blank: trains
Third blank: cars

(If the blanks have dropdown options, the most appropriate choices based on the text are:
Rail trails are \boxed{good} because they let bikers avoid city streets. The trails are built on old routes that \boxed{trains} no longer use. So, bikers can ride for miles without coming near \boxed{cars}.)