Starting from 2001, each denomination in the series was upgraded gradually.

The craft's firepower cannot be upgraded gradually, the best the player can do is pickup or buy cheaper weapons and hope to save up for the expensive ones.

The BMP-1P was in production by the late 1970s and existing BMP-1s were gradually upgraded to the standard during the 1980s.

With growth of American automobile usage, urban and rural roads were gradually upgraded for the new traffic.

Most other hardware parts are gradually upgraded with increasing series number.

The highway was gradually upgraded to a two-lane paved roadway.

The machines have been gradually upgraded, but they are no match for the most skilled human cutters.

In recent years, the authorities have gradually upgraded to more modern vehicles to expand the fleet.

Even in strongholds of rock-climbing tradition like Yosemite National Park, many routes are being gradually upgraded to safer standards of protection.

Throughout most of his career, Deuce has worn numerous masks that have upgraded gradually through time.