Donno gurai (どんのぐらい）＋ particle in the sentence?

[Yakultcat]

Hi, sorry, I'm a bit useless with particles, could someone help with this question?

I know if I just want to say how long + verb I don't need a particle, but when I want to add a noun I start getting confused...
So - どんのぐらい 勉強していますか？ －How long [are you/he/she/it/whatever] studying?

However if I want to clarify things, am I using the wo particle correctly in the below sentence?

今日、彼は日本語をどんのぐらい勉強していますか？ー Today, how long is he studying Japanese for? (i.e. he's studying right now and I'm asking this of his teacher or something...)

Japanese is the object of my sentence (I presume, with 'he' being my subject), so a) I need an object marker? and b) it's in the right place?

Thank you!

 

[Toritoribe]

どんのぐらい is usually not used. That's どのぐらい or its colloquial form どんぐらい.

Japanese is the object of my sentence (I presume, with 'he' being my subject), so a) I need an object marker? and b) it's in the right place?

a)を can be omitted and b) 彼は, 日本語（を） and どのぐらい are interchangeable with each other in the example sentence.

 

[Yakultcat]

どんのぐらい is usually not used. That's どのぐらい or its colloquial form どんぐらい.

Aaah! Thank you Toritoribe! This is why I couldn't find any English grammar sites on "どんのぐらい"...

So a) I can say - 今日、彼は日本語どのぐらい勉強していますか. Would this go for any similar structure, so I can use this formula - [time period], [pronoun/name は] [noun]どのぐらい[verb]? e.g. [明日]，[ベンさんは][テニス]どのぐらい[しましたか]. Then, if I've understood you answer to b correctly, I can move these around a bit, so [time period], [noun]どのぐらい[pronoun/name は] [verb] would work just as well?

b) Sorry I didn't quite understand - I can reorder the words in the sentence and the object remains the same? 今日、日本語, 彼はどのぐらい勉強していますか - Although in this version would I still omit wo? Is this because the subject is obvious from the context?

 

[Elizabeth]

Reversing the order is acceptable of course but どのくらい is usually expected before the noun in my experience (どのくらい英語を勉強...). :?

 

[Toritoribe]

Aaah! Thank you Toritoribe! This is why I couldn't find any English grammar sites on "どんのぐらい"...

So a) I can say - 今日、彼は日本語どのぐらい勉強していますか. Would this go for any similar structure, so I can use this formula - [time period], [pronoun/name は] [noun]どのぐらい[verb]? e.g. [明日]，[ベンさんは][テニス]どのぐらい[しましたか]. Then, if I've understood you answer to b correctly, I can move these around a bit, so [time period], [noun]どのぐらい[pronoun/name は] [verb] would work just as well?

b) Sorry I didn't quite understand - I can reorder the words in the sentence and the object remains the same? 今日、日本語, 彼はどのぐらい勉強していますか - Although in this version would I still omit wo? Is this because the subject is obvious from the context?

しました is the past tense and 明日 is future.;-)

The polite form 勉強していますか shows that it's used in a formal situation, so to omit を could sound awkward depending on the order of the words. In a colloquial conversation, you can also omit は, and 今日, 日本語（を）, 彼（は）, どのぐらい are all interchangeable each other. Thus, even どのぐらい日本語彼今日勉強してんの？ is acceptable as a spoken language.

 

[Yakultcat]

しました is the past tense and 明日 is future.;-)

Oh dear, I really need to watch out for that... The second time I've made that mistake on the forum and I've only posted about 15 times!

That clarifies it for me though, thanks both!