The most useful object in the world is a screw. not kidding
The most appropriate and most common exercise machine for home use is treadmill.
the world's most amazing machine may be the human body itself
50 cal. machine gun. i don't know who decided to use it.
What the most useful machine is, is a matter of opinion. Some would argue that the wheel is the most useful machine, and others would argue that the lever is the most useful.
The machine gun was introduced along with the use of airplanes.
They were a powerfull defensive weapon.
Most of the parties involved already had machine guns in their inventory prior to the outbreak of the First World War.
The 30.cal machine gun.
because they are very important to the world and we use them everyday such as a wheel and axle that are used on doorknobs.
Machine guns were in use BEFORE WW 1. They were around for the entire war.
The use of a commercial coffee machine is to make coffee fast in the morning. Most people need coffee to function in the mornings. That is the use of commercial coffee.
Tanks and machine guns.