way：普通用语,与in搭配.用于处理任何事物的方法 in the way
method：合乎逻辑、科学系统的方法,与with搭配with method
approach：常与to搭配approach to
means：单复数同形,与by搭配,表示为达到某种目的而采取的方法by means of

At the meeting they discussed three___to the study of mathmatics.
A. approachesB.means. C.methodsD.ways
选A
题中的B.means C.methods D.ways 方法 后面都是与of连用.其中way 后面可加to do/of doing