The study of elementary particles is an important field in physics.

The tire tracks of the car were left on the snow.

He was observing the behavior of birds.

He was observing the behavior of the birds.

Early in the morning, the mist was thick and visibility was poor.

He went to Tokyo yesterday and hasn't come back since.

Kiri is my best friend.

He proceeded with the conversation in a tight manner.

Strict discipline is maintained at this school.

Everyone stood up when the teacher came in.