That I should

Quick question that’s been bugging me.

If I want to say something like “I know that I should run”, what (southern) options are available for “that I should”. I’ve found lots of options online, so I’m starting to confuse myself.

Same question for sentences containing “that I shouldn’t”.

Any help much appreciated.

Hi Steve,
I’ll be interested to see the right answer to this, too. I’d say “Dwi’n gwbod bod dilai’ni(sp?) rhedeg”, but as with all things I expect to be wrong :slight_smile:

Dw i’n gwybod y dylwn i fynd / ddim mynd would be my take on this Steve.



Or could it be: Dw i’n gwybod bof i ddylwn i… / bof i ddylwn i ddim?

“Dw i’n gwybod [y] dylwn i redeg” would be what I would say, (which means next to nothing!) I would assume that the [y] is usually left out in speech, but I could well be wrong.

Just to explain a little- “bod” does not ‘mean’ “that”.
It is the form the verb “to be” takes when it is in a “that” type construction.
If the verb “to be” is not there, the little [y] particle is used to join the two parts of the sentence. {Or just left out entirely, of course! As it can be in Engish. “I think that I should go”=“I think I should go” (and on that note…)

Hope of some use, if it makes no sense it is my failure to explain it properly, and it isn’t important!

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After I posted my suggestion, I asked Gwyn (my partner, who is a native Welsh speaker) and he confirmed the structure as “Dw i’n gwybod y dylwn i rhedeg” - which is what Owain and Stu recommend. Gwyn also confirmed that the “y” is sometimes omitted. Steve also wanted to know about the negative: Gwyn suggested Dw i’n gwybod na ddylwn i rhedeg", but if you just want to say " I know I shouldn’t" then it would be “Dw i’n gwybod y dylwn i ddim”.

I know ‘bof i’ is from bod, but it seems to crop up in all sorts of sentences in SSiW gogledd, so thought it might work here.


Thanks for this Anne! The use of na like this is something I am having to work really hard on, and it was brilliant timing to be reminded of it just now.



It’s very slangy - and more ‘bo fi’ - ‘bod fi’ - instead of ‘fy mod i’ :sunny:

Croeso @essenbee. I too struggled with “na” - but when Gwyn and I were discussing the way to say “I know I shouldn’t run” - I actually said it first, and he confirmed it! I could hear it in my head!

Thanks @aran for the correction on the written ‘bo fi’ - makes perfect sense.

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(I know I should go back and revise a few (dozen…) lessons, but (if it’s possible to give a short answer), when do you use “bo fi” (or its less slangy forms), and when do you use the (seemingly) more simple construction with an optional “y”? (or “na” if it’s negative).

I’m hopeless with ‘rules’, but basically my experience is that you need bo’ fi (or whatever is your preferred version) if what follows is a present tense statement (or adjective, thinking about it). Other tenses don’t need this.

Dwi’n sicr bo’ fi’n mynd.
Dwi’n sicr bo fi’n hapus.


Dwi’n sicr (y) bydda i’n mynd.
Dwi’n sicr (y) byddwn i’n mynd.
Dwi’n sicr (yr) o’n i’n mynd.


What Robbruce said. Maybe I can add a tiny bit-

It’s when you are joining two sentences and the second one begins with a form of the verb “to be” in the present tense.
“Dw i’n siwr” + “Dw i’n mynd” etc.
It is the form the present tense of the verb “to be” takes in this sort of sentence.

If the second bit does not begin with a form of the verb “to be” in the present tense, eg “Bydda i”,
or does not begin with any form of the verb “to be” eg “dylwn i”

then that elusive (y) appears instead.


Very useful, Owain!

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Bingo! Diolch yn fawr Rob a Owain.

(EDITed for dragon :slight_smile: )

Shone a light for me too…Diolch!