Sentence examples for improvements have been from inspiring English sources

Improvements have been made.

Of course, improvements have been made.

Various improvements have been made since then.

What improvements have been made?

But improvements have been made.

Since 2007, significant improvements have been made.

Nevertheless some important improvements have been made.

Various extensions and improvements have been proposed.

These improvements have been validated experimentally.

But those improvements have been eclipsed by corruption.

In some areas, the improvements have been dramatic.