What's the difference between -ga and -o when they are used to designate a direct object?


During the past month I've been addicted to Japanese. I've listened to about
10 online tutorial video courses and read about as much printed lessons. I am
determined to learn Japanese, but I am really a newbie so my question may be
very basic, but please bear with me.

If I understand correctly, both _-ga_ and _-o_ particles designate a direct
object. For example, I've heard:

> Watashi wa ongaku-ga suki desu. = I like music
>
> Watashi wa ongaku-o kiku (or kikimasu, I'm not sure) = I am listening to
> music

So why is it _ga_ in one case and _o_ in the other? Is it specific to the verb
or the object or what?

P.S. I don't know hiragana yet, so I'd appreciate if you could keep your
examples, if any, in romaji.




It depends not only on the verb, but on the form of the verb.

The general rule is that static verbs and adjectives take "ga" and "action
verbs" take "o" on the direct object.

> piano-o hiku  
>  play the piano
>
> piano-ga hikeru  
>  can play the piano

Here, playing the piano is an action, thus "o" is used. Being able to play the
piano is a state, thus "ga" is used.

> ringo-ga hoshii  
>  want an apple
>
> ringo-o hoshigaru  
>  act like you want an apple

Again, to want an apple is a state, so use "ga", to act like you want it is an
action, so use "o".




It depends not only on the verb, but on the form of the verb.

The general rule is that static verbs and adjectives take "ga" and "action
verbs" take "o" on the direct object.

> piano-o hiku  
>  play the piano
>
> piano-ga hikeru  
>  can play the piano

Here, playing the piano is an action, thus "o" is used. Being able to play the
piano is a state, thus "ga" is used.

> ringo-ga hoshii  
>  want an apple
>
> ringo-o hoshigaru  
>  act like you want an apple

Again, to want an apple is a state, so use "ga", to act like you want it is an
action, so use "o".

