Bob ran down the road.
He fell over.

Bob fell over because he ran down the road.

The thunder roared.
The hobbits hid.

The hobbits hid since the thunder roared.

Bilbo slept in a cave.
The goblins attacked.

The goblins attacked because Bilbo was asleep in a cave.

The cart came to a wheezing halt.
Gandalf strode into the hobbit hole.

Gandalf strode into the hobbit hole because the cart came to a wheezing halt.

Jim was interested in the idea.
He rang his friend.

He rang his friend, so Jim was interested in the idea.

Owls are nocturnal.
This means they are active at night.
They have excellent eyesight.

Owls, who have excellent eyesight so this means they are active at night.