blue
The word 'blau' in German is used to describe the color blue. It is a common color term and is used in the same way as 'blue' in English. For example, 'Das Auto ist blau' translates to 'The car is blue'.
The sky is blue.
This is a simple declarative sentence stating a fact about the colour of the sky. In German, the word for 'sky' is 'Himmel', and 'is' is translated as 'ist'. This sentence follows the typical subject-verb-object sentence structure used in English and German.
His favorite color is blue.
None
The car is not blue, but red.
This is a complex sentence using the word 'sowohl' which renders the translation as 'not only... but also...' to emphasize that something is not just one thing but another as well. In this case, it's used to clarify that the car is not blue but red. 'sowohl... als auch...' is a common phrase used in German to express this kind of idea.