Answer:
When it comes to me, you go on red and stop on green. What am I?
What is so delicate that saying its name breaks it?
I plow and plow but never sow.
The Titanic is still here. What am I?
I am a ship that can be made to ride the greatest waves. I am not built by objects, but built by minds. What am I?
It flows out of the soil, It burns you if it boils, And holds us in its coils, More valuable than gold, As black as it is old.