The world we see with our normal sight is actually more limited than we think.

He made a clear and definite statement about his position on the issue.

He stated his opinion clearly.

He has a habit of spouting insensitive words.

It's difficult to find the original image of this figure.

He likes to develop film by himself.

What is this cause of the disease?

He measures time accurately using an atomic clock.

The atomic weight of helium is 4.

There is always a debate about the safety of nuclear power plants.