The idea that lightening was electricity struck Ben Franklin like a bolt from the blue.
The sky is blue.
I feel blue when i am sick and unhappy.
Blue Alcopop
The young girl stared at the blue sky for several hours.
The sentence "Use the blue key, not the yellow key" should use a comma before the phrase "not the yellow key" to separate the two contrasting elements.
bluish means light blue
The cormorant sought fish in the blue ocean.
The correct way to punctuate the sentence is: "You should use the blue key, not the yellow."
The teen dyed her hair blue, but her parents disproved of it.
the guy was wearing a long blue turban
My right eye's color is blue.
If the respective man is sitting, standing or lying ON a blue dress then, yes, it is a correct sentence. If you use IN instead of ON, then he is wearing a dress.