There are a few main theories about the origin of the signs.

Two main theories have been proposed to explain the development of the disorder.

There are two main theories as to the origin of the tag.

But the other main theories are seen as having less hopeful implications.

The other main theory for the extinction was due to the climate change brought on by the most recent ice age.

There are four main theories as to the meaning of the name.

The men are charged with capital murder in Virginia on two main theories.

There are two main theories regarding when modern human behavior emerged.

There are two main theories for why people eat more in bigger groups.

Well, the main theory was that she fell into the river on one of her walks.