"Are you still in the marine?"
No, "marine aviator" is not capitalized in a sentence unless it is part of a specific title or name. Generally, it is treated as a common noun, so you would write it in lowercase. For example: "The marine aviator completed his training."
My luggage is still in the room!
I am still able to write with my right hand.
you use the code "<S> write the sentence here </s>"
Yes, it counts as a sentence, as long as you have a noun, subject, or verb.
After all, they still nee to write commands.
I'm not that those salad greens are still edible.
The water in the pond was still and deep. He heard a still, small voice. The bootleggers used a still to make moonshine.
Even though you are not nice to me but I am still like you my friend?
No matter how many times I did the calculation, the answer still came to 3.100.
No, you do not capitalize marine biologist in a sentence. (Unless marine is in the beginning of the sentence)
Unknow isn't a word, but "unknown" is. Sentence: The world of aliens is still UNKNOWN to humans.