He was able to solve the complex calculation quickly.

He was calculating in his head.

We are considering introducing a new voting system.

We have developed a new methodology to solve this problem.

Learning a new input method is difficult.

There is a class observation at my son's school tomorrow.

The use of mobile phones is prohibited during class.

He is an expert in harmonic analysis.

That painting is incongruous with the room's decoration.

There was discord between them.