"South America is big."
Translation:Mae De America yn fawr.
I believe the X ydy Y / X yw Y construction is used for identification: when you're answering questions such as "Who is the doctor?" or "What is John?" or "What is the best novel there is?" or "What is the capital of Brazil?".
Here, you're not identifying a country; you're simply asserting a quality.
Not quite. The difference is rather one of emphasis.
In Welsh the verb always likes to sit at the front of the sentence. Thus the normal form of a sentence is "Mae X yn Y". However, as with many other languages, you can add emphasis to something by changing the word order, bringing it to the front of a sentence. Thus X ydy/yw Y. In the latter formulation, it is being expressed that X (and not something else) is Y. In the emphatic form you might stress X is Y or indeed that Y is X.
Some examples as all those X's and Y's just look confusing:
- Mae ceffyl yn neidio - A horse is jumping
- Neidio ydy'r ceffyl - The horse is jumping (not walking like you would expect perhaps)
In this example:
- Mawr yw De America - Big (and not small) is south America
- Mae De America yn fawr - South America is big.
mizinamo is not wrong to mention identification, however. There is one time we are always emphatic, and that is when talking about who we are. Must be an ego thing! So:
Stephen ydw i - I am Stephen
Never would you say "dw i'n Stephen". Always be emphatic about that. I am Stephen, and no one else!
It occurs to me that I did not explain that "mae" and "ydy" as well as "yw" are all the same verb here. To be is irregular in Welsh as it is in most languages, and this is one of the most irregular forms. If third person singular form of to be is used at the start of a declarative sentence then it is "mae". If it starts a question, or is used in the emphatic form it is "ydy". So:
- Mae De America yn fawr - South Americal is big
- Ydy De America yn fawr? - Is south America big?
- Mawr ydy De America - South America is BIG
And then just to confuse things, yw is interchangeable for ydy in the emphatic form only:
- Mawr yw De America.