He finished his work in a short time.

In mathematics, the commutative law applies to addition and multiplication.

Let's exchange keys tomorrow.

We write in the exchange diary every day.

We wrote essays for peer grading.

He works at the switchboard.

A drop of water fell from the cup.

He knows the knack of cooking.

He gathered the wood chips and started a fire.

He set off on a journey to the north.