だけ means "just/only" and shows the extent/limit of something. だけ can also be after verbs, adjectives, etc that are in the れんたいけい. So, いやなだけ not いやだけ. This is because it's actually from the noun 丈（たけ）, which means "length".
|Noun + だけ||形容詞 ＋ だけ||形容動詞 ＋ だけ||Verb ＋ だけ|
|手 ＋ だけ → 手だけ||ほしい ＋ だけ → ほしいだけ||好き ＋ だけ → 好きなだけ||話す＋ だけ → 話すだけ|
Particle Note: が and を are optional after だけ. Don’t put them before it.
I became uneasy just at the thought of the test.
Please give me five red apples only.
I only love you.
I only study English.
You can't tell a person just by looks.
Please overlook just this one time.
There is only 1 person.
To carry just what one wants.
He only did the laundry last weekend!
She only did cleaning last weekend!
だけで｛（は）・じゃ｝なく means "not only".
Not only are there cats, but there are also dogs.
That room is not only spacious, but it's also very bright and beautiful.
だけ（のこと）だ states that there is nothing more than something. So, it can be translated as "...is no more than". With the inclusion of のこと, the statement is more forceful.
I only caught a cold.
It's just that the company went bankrupt.
I'm just looking.
I only grazed my knee.
Speech Level Note: The deletion of だ makes だけ a final particle. It makes the sentence less blunt. だけです is perfectly fine for polite speech.
With これ, それ, あれ, and どれ, だけ translates as "much".
These are the only useful sites.
I've collected this many tickets.
20. それだけなの？(A little feminine)
Is that all?
The beginner's book is really expensive, but it has the worth.
No matter how hard it is, I won't let go.
だけ shows a limit, and in this expression you make it even more clear that you are not expecting, wanting, or doing any more.
As for this, it's best that you at the most talk to your parents.
I'll wait quietly for the results since I did what I had to do.
I feel good now that I've said (what I had to say).
Come on, at least listen to what I have to say.
Potential + だけ
With the potential form of the verb, it can be translated in this way as "as much as...".
Do as much as possible.
I ran as much as I could.
なるべく VS できるだけ
Both mean "if possible/as (much) as possible". なるべく is (somewhat) formal. できるだけ can be followed by の. To use it with なるべく , you have to use the rare なるたけ/なるだけ.
As much as possible/if possible, do not smoke.
Grammar Note: な in the above sentence creates the negative imperative.
I would like you to come during the afternoon if possible.
I need as much money as possible!
Please come home as soon as possible.
As an adverb, ただ means "just what you're doing". For example, "you're just hoping that you get a good grade in Japanese class". Other synonyms include 専ら and ひたすら. Or, it may stress that there's "nothing else" or that there is "merely" something. Other words for this include たった and わずかに.
ただ...だけ means "mere(ly)", but だけ isn’t necessary. 専ら ≒ "entirely", so there is no need for だけ. Neither is there a need for it with ひたすら. ほんの僅か...だけ = "just a few". たった comes from ただ to mean "mere" and is frequently used with だけ.
It disappeared just now!
Culture Note: Whenever you come home, you say ただいま. People there will response with お帰り（なさい） "welcome home". The added part makes it polite.
It's widely rumored.
With just a mere excuse
Isn't that just a problem of degree?
Word Note: 単に means "purely/simply/merely" and is also often used with だけ.
I merely stated my own opinion.
Word Note: 私の意見ではis wrong, but 私見 is OK.
Nuance Note: Simply as in "easily" can be 単純に, 簡単に, 単に, etc. with just slight differences. The first shows a heavy emphasis on simplifying a process down. The second shows more so the easy, and the latter emphasizes on the extent of the matter.
It's just 10 kilometers to Tokyo.
42. あられがほんのわずか降っただけだ。(Somewhat written style)
There was only a light amount of hail that fell.
Just one time
Word Note: ほんの is an attributive phrase that means "mere". So, it is often used with particles like だけ and しか (see below). ほんの少し means "just a little". The word gives the sense that there really is nothing else beyond it. It can also be written as 本の.
It's probably just a cold.
Word Note: 風邪 means "cold" but comes from and is pronounced just like 風 (wind).
Nothing costs more than what is given to us.
There is but one way to live.
Beauty is but skin-deep.
ただでは in a negative sentence means that something serious is to happen.
You'll pay for this!