Experts said the retrovirus was probably not the sole factor in the boy's illness.

The sole ultimate factor in human decisions is physical force.

But it is not the sole factor, he said.

Firepower was not the sole factor in a contest of this nature, however.

Middle class guilt is unfortunately the sole motivating factor for a lot of people.

He said that the demand of the campaign was the sole factor in that decision.

This index is usually the sole factor considered when applying for university courses.

Moreover, the social environment is not the sole factor in how we become ourselves.

The deception need not be the sole factor in obtaining.

This exam is the sole and only factor considered for entry into third level education.