This is something that came out in another thread and that I pointed out asking for a confirmation from a native speaker, but I guess no one ever noticed it LOL.
I assume you know (and if not you will know it now) that there is a conjugation to make potential forms of verbs like 行く=go and 行ける=can go. This way you can avoid using the form ことができる. できる itself is the potential form of a verb which is the verb to do する.
So theorically it wouldn't make much sense say 。。。することができる being する and できる the same verb. Yet if you google it, you will find many milions of those forms used in the web....thus not sure what to think. I personally try to avoid using することができる.

heys i wasn't aware of this form of conjugation. does this apply to all verbs, and how exactly is it done?

Yes it can be done to all verbs.

most are pretty straightforward like

行く＝行ける、買う＝買える、飲む＝飲める

just look at your hiragana chart and change the verb ending to the え sound and add る

a little caution. many verbs that end in る are conjugated like this...
食べる＝食べられる、変える＝変えられる

but some verbs that end in　る also simply just conjugate to the え sound plus る like 帰る＝帰れる how does one tell the difference between which verbs in dictionary form that end in る　use the え pattern and which use the られる　pattern...？ I dunno.. I would always just pay attention to the past tense of verbs .. you can tell that 食べる changes to 食べられる because the past tense of 食べる is 食べた.. whereas, you know that 　帰る is 帰れる, because the past tense is 帰った。

Or even you can look at the ます form of the verbs to know.. 食べる＝食べます
帰る＝帰ります。

It might seem confusing now, but with the right amount of memorizing and practicing and it will be nothing to you in no time.

I do not know where you are at right now but if you are a beginner, i suggest when you learn a new verb concentrate on its present tense polite forms, past tense conjugation in both polite and plain forms, negative conjugation in both plain and polite, てーform (request form), and potential form (what we are talking about)

To simplify what RickOShay said, there are two types of verbs. Ichidan and godan.

Ichidan verbs are ones that drop る and add ます in polite non-past. 食べます、止めます, etc. Every ichidan ends with /eru/, but not every verb ending in /eru/ is ichidan.

Godan verbs are everything else except する／来る (the two verbs considered irregular most of the time). You can think of them as the ones that drop and add /imasu/ to the stem for polite non-past. 飲みます、作ります, etc.

For the potential form of ichidan verbs, drop る and add られる. For ichidan verbs, you change the stem's ending to /e/ and add る.

Examples:
ichidan
食べるー＞食べられる
止めるー＞止められる
godan
飲むー＞飲める
作るー＞作れる
irregular
するー＞できる
来るー＞来（こ）られる

I'd suggest reading Tae Kim's guide (or a textbook, really) to get a better explanation than we are willing to type here. It's not like it's an esoteric thing that isn't explained in every Japanese textbook on the planet.

And learn the terms "ichidan" and "godan." It will make it much easier to explain things in the future.

Yeah, I agree. In my first Japanese text book way back when.. it never taught us those terms.. the verbs were simply referred to as るverbs and うverbs. So every time I tried to explain to Japanese people that I had no idea how to conjugate verbs ending in dictionary form る that I was unfamiliar with, they could never understand what I meant. I had to draw it out for them.

BTW.. is there anyway you have heard of to tell which they are for the ones that end in dictionary form る other than through experience？

You've got the guideline really wrong.

Every verb that does not end in /eru/ or /iru/ is definitely a godan verb. Most that end in /eru/ or /iru/ are ichidan verbs. It's not /ru/ verbs, but /eru/ and /iru/ verbs.

For example, 止まる is a godan verb even though it ends in る. On the other hand, 止める is an ichidan verb because it ends in /eru/, and in general, verbs that end in /eru/ are ichidan.

There are exceptions, such as 帰る, which ends in /eru/ but is a godan.

In general, here's what you should be thinking, provided it's not instinctive at this point:
1. Do I know whether this verb is ichidan or godan already? If so, stop. If not, continue to #2.
2. Does it end in /eru/ or /iru/? If no, it is godan. If yes, it's probably ichidan.

Here's a good example of why you have to just memorize some of them:
いる (to exist)->います
いる (to need)->いります

One other thing to note: It's entirely possible natives don't know these terms ichidan and godan. I wouldn't be surprised if Sashimister wasn't aware of this distinction. Since Japanese people don't have to learn the rule, they don't need the terms. It's more of a linguistics thing.

It's like how native English speakers don't (in general) learn certain terms for English (past pluperfect, e.g.), but can just use the rules without being taught them.

cool i've just read through TaeKim's guide. its really good!

anyway just to check, would this be alright: シさんは卒業できる
and is it true that i should avoid using this: シさんは卒業することができる

(also will i be able to change the こと to a の as such: シさんは卒業するのができる)

Where do you find these unusual names? ;)

First two sentences are correct but not the last.

Since when? :confused:

lol i was thinking along the lines of Mr-A, B, C

would シさんは卒業することができる by any way sound weird?


also is it true that の can be used to change a verb into a gerund, if so what modifications must i make to the third sentence valid (3rd sentence: シさんは卒業するのができる)