Why is the particle を used in this sentence?


I found this example in a japanese textbook:

  * > 外を歩いている人はみんな傘をさしています: Everyone is using umbrellas outside.

Why is を in that sentence?, and because it is a japanese textbook I doubt that
it is inconrrect, shouldn't be like this?

  * > 外に歩いている人は傘をさしています




Verb of movement can take を to express the idea of moving about within that
space. So here, 外を歩いている expresses the idea of "walk around outside". In a
similar vein 空を飛ぶ means "to fly through the sky".

外に歩く isn't quite grammatical in the sense which you seem to have in mind;
instead it means "to walk toward the outside". It would be better to say, 外で歩く
but it doesn't have quite the same feel as 外を歩いている. 外で歩く seems to suggest that
there are other places where you could have chosen to walk--maybe you're at a
convention and you could walk inside the convention center or outside. But,
外を歩いている carries a connotation of walking about outside with perhaps no
particular destination in mind.




Verb of movement can take を to express the idea of moving about within that
space. So here, 外を歩いている expresses the idea of "walk around outside". In a
similar vein 空を飛ぶ means "to fly through the sky".

外に歩く isn't quite grammatical in the sense which you seem to have in mind;
instead it means "to walk toward the outside". It would be better to say, 外で歩く
but it doesn't have quite the same feel as 外を歩いている. 外で歩く seems to suggest that
there are other places where you could have chosen to walk--maybe you're at a
convention and you could walk inside the convention center or outside. But,
外を歩いている carries a connotation of walking about outside with perhaps no
particular destination in mind.

