This rare plant is threatened by a number of forces.

Its limited range is threatened by a number of forces.

"But there is simply nothing to suggest that the number of American forces would need to increase," the official said.

In natural populations there are a number of forces acting.

They also said that the outcome could be influenced by a number of outside forces.

Despite the large numbers of forces involved, there had been no major battles.

But a number of powerful forces were also in play.

It took the total number of British forces to die in the conflict to 141.

It increased the total number of British forces to die in the conflict to 145.

It takes the total number of British forces to die in the conflict to 150.