"That is my first impression."
Translation:Das ist mein erster Eindruck.
Yes, but that is not the only reason. Other ones are:
- it is in nominative case
- a possessive adjective (mein) is preceding it = mixed inflection http://en.wikipedia.org/wiki/German_declension#Mixed_inflection.5B6.5D
masculine gender + nominative case + mixed inflection = "erster"
http://www.canoo.net/inflection/erste:A:Ord (check Gemischte Flexion)
My interpretation is that "Das" is the subject of the sentence and "Eindruck" is the object. Therefore, since Eindruck is masculine and preceded by mein, erst would take the form ersten. Can this sentence be interpreted two ways, with Eindruck as the subject and Das as the object?
Thank you! I had no clue about predicate nominative, but it's pretty simple after I looked it up. This video might help others: http://www.youtube.com/watch?v=USWU0Dcl7fQ
It's kind of slow and he's a little redundant which is odd because his target audience is little-to-no-attention-span high schoolers :P
Since Eindruck is in the nominative case (predicate nominateive) and it is masculine, the adjective ending is -er. See this page http://www.babelnation.com/german/courses/01_07_8.html