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When we have a する verb (e.g. 支度する、案内する、心配する), is it true that we could optionally insert an を particle in between the noun and the する?

Because in the example sentences here and here, we can see this usage (the usage of を particle appearing between the noun and the する).

So basically am I right to say that for all する verbs, we can optionally include (or exclude) an を particle in between the noun and the する?

If not, how exactly should we decide whether or not to include that を? I mean I know with a lot of usage we will just know it, but are there any rules that we can apply here?

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up vote 17 down vote accepted

Here are the only two exceptions I can think of where you absolutely can't insert "を":

If the construction wasn't based on をする but とする like さっぱりする→◯さっぱりとする ☓さっぱりをする

If the construction is "merged" single character する verbs like 動じる/動ずる、案じる/案ずる、命じる/命ずる、失する、課する、罰する etc.

However, it's uncommon to just add を in in many cases - so the result may be awkward if it's without precedent. Basically, adding an を adds emphasis on the noun the verb comes from, rather than the action that する notes. Think of 支度をする and 支度する as "to do preparations" vs. "to prepare" - either sound fine, but 誘拐をする and T "to do(?) a kidnapping" vs. "to kidnap" It's not exactly like that, but I guess I'm trying to show how some cases like with 誘拐 it would sound awkward.

Also something to note is that if you're adding a "を" for instance with 掃除をする. You can't add another "を". 部屋を掃除をする you would write it as 部屋の掃除をする - however this isn't a problem if you've omitted the を. For instance with 子どもを誘拐する. Again, 子どもの誘拐をする would be grammatically "correct" but would sound extremely "off".

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With 「~とする」 it's actually a と-adverb construct so using 「を」 would be silly. – Ignacio Vazquez-Abrams Jun 26 '11 at 19:32
btw do you know why is it that 課する is considered a "merged suru verb" ? – Pacerier Jul 5 '11 at 22:22
@Pacerier mainly just because it's its a single character's ON reading + suru (as it is in all other examples), but also because my dictionary lists it as (vs-s) rather than (vs). – Kafka Fuura Jul 6 '11 at 5:35
as for the "zuru" verbs, I was wondering how do we conjugate them. is it that 命ずる becomes めいずります ? – Pacerier Jul 6 '11 at 10:19
@Pacerier It would become 命じます. Sorry for the late response; "zuru" verbs were originally sa-hen verbs like all the other -"suru" verbs, but most have "transformed" into ichidan verbs. 命ずる becomes "命じる" and acts like a ichidan verb most of the time. However in certain constructions it retains its original sa-hen conjugation. Like in 命ぜざるをえない. Occasionally I've seen "zuru" verbs used like this 信ずる方 "believer" in rentaikei, but nowadays they mostly act as ichidan verbs. (ie. you say 命じない/信じない instead of 命ぜない/信ぜない) – Kafka Fuura Jul 8 '11 at 10:56

I can't think of any long and detailed answer for that (sorry), but the short answer is:
Most of the times, yes.

For most verbs it seems like the choice between ~をする and ~する is entirely flexible. I think the actual difference between these forms may be related to focus: adding を puts a greater focus on the specific action described by the verb. Then again, I may be utterly wrong here.

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