form与ion不能直接组合，中间要加at， 构成formation.
n. 形成构造编队
The coach rearranged the formation for the match.
教练针对这次比赛重新编了队形。
Look at these rock formations.
看看这些岩层结构。
This cloud formation looks like an elephant.
He was flying in formation with seven other jets.
他和另外7架喷气式飞机编队飞行。
