In Japan, 4 and 9 are considered unlucky numbers.

He was working abroad for twelve months.

Let's get to work immediately.

We were given a tour of the factory by the person in charge.

He is undergoing training for extravehicular activity.

He engaged in an extravehicular activity from the spaceship.

We crossed the sea by catamaran.

The shipworm is known for eating wood.

When I happened to pass by the library, I ran into an old friend by chance.

In this experiment, we will measure the critical Reynolds number.