"I am sitting the exam today."
Translation:Dw i'n sefyll yr arholiad heddiw.
so the English sit an exam, but the Welsh stand an exam? (surely it should be "can't stand" for both of them? :-) :-) )
Sefylla i'r arholiad heddiw.
How do we know when DuoLingo wants us to use which tense? (It is confusing to be given, e.g. "os bydd hi'n braf" and marked wrong for "if it will be fine", because the expected answer was "if it's fine".)
By and large, the English and Welsh tenses are the same in the modern colloquial language. There are differences once you start looking at more formal Welsh, but that is beyond the scope of this introductory course.
There is a difference when using an if-clause starting with os..., though - where in English we say 'if the train is on time' (using the present tense to refer to something which has not yet happened), in Welsh we use the future tense 'os bydd y trên ar amser' . This is explained in the course notes.
(On a different point... When we are creating Welsh short forms of verbs by adding a personal ending to the root of a verb-noun, we need to know the root. In the case of sefyll it has an irregular root, saf-, so:
- safa i - I will stand
- safi di - you will stand
- etc )