This is a thing not to worry about

Question

Definite article still confuse me even after having got a lot of help on the site. What I noticed is that we use "the" when we talk about something particular or something unique. But what with this sentence:

1) This is a thing not to worry about.

I think if I said 2) "This is the thing not to worry about", it would mean that this is the only thing not to worry about, but what if I mean it's just one of them - should I use indefinite article then? But than it seems a strange structure to me...

Saying "this is a thing not to worry about" sound like "this is a case not to worry about" - never met such a thing. Never heard "that's a case either"...

So,

1) Is the sentence 1 correct?

2) Can the sentence 2 mean that it's one of the things not to worry about?

3) If the answer for the 2nd question is "yes", can I say: "I am lazy. This is the thing not to worry about. I am angry too. This is also the thing not to worry about." Or "a" should be used?

I know I asked similar questions, but still in a muddle and want to clarify this all... Thank you in advance!)

Answer 1

1) Sentence 1 is OK, but you can simplify it:

This is nothing to worry about.

This holds the meaning of thing (or whatever the subject is) so there is no reason to repeat it, unless it needs specific emphasis.

2) Yes.

3) The phrase I mentioned above solves the problem of whether to say a thing or the thing (your comment in 3) in your question, whether to use "a" or "the").

But if you want to use "a or "the" as in your example, I would stick with "a" unless you need to emphasize a particular "thing". It is unlikely to be "the" only "thing", as we all have plenty to worry about.

An example using emphasis might be:

You have been late to work a lot recently. Your attendance is the thing you need to worry about.

Answer 2

This is a thing not to worry about.

The above sentence is correct and the answer for your 2nd question is correct. The reason is as follow:

Regarding the above sentence an indefinite article "a" is used in-front of "thing" which is already introduced in the conversation. The indefinite article "a" is used to express the uncertainty of the nature of the thing expressed in the main clause.

For example:

I am lazy. This is a thing not to worry about

On the above sentence it is not sure on the first clause, whether being lazy is to be worried or not to be worried. To express this uncertainty the indefinite article "a" is used instead of "the". This kind of indefinite article usage can been seen on the sentences where the latter describes something about the former.