A man in a blue suit sits at a table with a laptop.
A man in a blue suit has a computer.
A man skydives.
Turtles ride dolphins often into private beaches to lay eggs.
The band is on stage
Someone was outside working on a roof.
Federal spending on infrastructure decreases national saving and investment.
We need to keep ourselves alive.
For a description of prototyping and the spiral model, see Roger S. Pressman, Software A Practitioner's Approach, 3rd ed.