This week it's St David's Day - Dydd Gŵyl Dewi. But sometimes you will hear people saying Dydd Gŵyl Ddewi, where they mutate the name Dewi. In fact, both versions are correct - the first version Dydd Gŵyl Dewi refers to the fact that it is the festival of Dewi -

Gŵyl pwy? - whose festival
Gŵyl Dewi - Dewi's festival of course!

The second version - Gŵyl Ddewi - describes the actual festival rather than explain whose it is and could be loosely translated as 'the Dewi festival'. Gŵyl is a feminine word, so any adjective used to describe it would have to take a soft mutation -

gŵyl dda - A good festival
gŵyl ddiflas - A boring festival
Gŵyl Ddewi! - Well - a David festival!

We all know that Dydd Gŵyl Dewi falls on March the 1st But in the same way that we can say in English either March the first or the 1st of March we can say in Welsh - Mawrth y cyntaf or y Cyntaf o Fawrth. Of course if you use the second pattern - y Cyntaf o Fawrth - you must remember to mutate the month after the preposition 'o'. So Mawrth becomes Fawrth.

In other examples:

Tachwedd (November) could be Tachwedd y cyntaf or y Cyntaf o Dachwedd

Mehefin (June) could be Mehefin y cyntaf or y Cyntaf o Fehefin

Gorffennaf (July) could be Gorffennaf y cyntaf or y cyntaf o Orffenaf.

Both these patterns can be used for all dates and all months.

Jenny gets chatting to her friend Agnes and starts to tell her a story . She's convinced that Chris is stalking her.

Jenny - Felly ar ôl i mi barcio'r car...Dyma fi'n camu allan ac wrth i mi gloi'r drws...Dyma fi'n gweld Chris yn sefyll wrth y trolis...

Jenny uses the form dyma + the person + the verb here. It's a technique used a lot in Welsh when we relate stories to each other. It could literally be translated as 'here I was' - "here I was doing this, then here I was doing the other" meaning simply "I did this, then I did the other". It's an easy way to avoid using the past tense and trying to remember how to conjugate the verb ot where to mutate. But remember that you can only use this form when using the past tense in a story. It also works in every person. Here are some examples:

Dyma ni'n mynd allan - We went out
Dyma fo'n fy ngweld i - He saw me
Dyma Mam yn chwerthin - Mam laughed
Dyma fi'n rhedeg - I ran