to concentrate a military force

集中军力。

The company concentrates orange juice and sells it in small cans.

这家公司浓缩橘子汁以小罐出售。

He concentrates his attention on the problem.

他集中注意力在这问题上。

The population in our country concentrated in the cities.

我国的人口集中在城市。

Bill could not concentrate on his homework because the room was too noisy.

比尔无法集中精神做功课，因为房间太喧闹。