"は + verb" instead of "を + verb"?


I have stumbled upon instances where "は + verb" is used in situations where I
thought "を + verb" should be used. For example, recently I've seen

> その覚悟はしてました  
>  I was prepared for that
>
> 楽な道は選ぶな  
>  don't choose an easy road

Is there a difference? And if there is, what's the "rule" when to use は
instead of を?




は is normally used a subject marker, but its also used for emphasis by
slightly subverting its standard usage. When used this way, it's usually to
show contrast the object with some other object. In your example sentence
(その覚悟はしてました), the speaker indicates that they're prepared for the eventuality
that their conversation partner just mentioned, but maybe not some others.  
「無線機をなくしたら、どうしますか？」  
「その覚悟はしてます。シグナル鏡を持っていくつもりです。」  
「シグナル鏡をなくしたら？」  
「そのときは、仕方がありません。」




は is normally used a subject marker, but its also used for emphasis by
slightly subverting its standard usage. When used this way, it's usually to
show contrast the object with some other object. In your example sentence
(その覚悟はしてました), the speaker indicates that they're prepared for the eventuality
that their conversation partner just mentioned, but maybe not some others.  
「無線機をなくしたら、どうしますか？」  
「その覚悟はしてます。シグナル鏡を持っていくつもりです。」  
「シグナル鏡をなくしたら？」  
「そのときは、仕方がありません。」

