In this factory, they are melting iron using an electric arc furnace.

He is learning the technique of arc welding.

He conducted an experiment using an arc lamp.

My keys are inside the house.

He is quite a good cook.

I think his Japanese has improved quite a bit, hasn't it?

I am busy with work during the daytime.

He is an expert in embryology, studying the developmental processes of many kinds of organisms.

The process of embryogenesis is very complex, with continuous cell division and differentiation.

He went to try out his new air gun.