one third of是单数还是复数

　　But this third group was not only unexpected, it was so distinct and so large--nearly one third of our sample--that it became a key finding of the study.

　　但是这个第三类群体不仅是出乎意料的，而且十分明显，数量庞大——占我们样本数量的三分之一——成为这个研究的关键性发现。

　　More than one third of those asked said they would not run to catch a bus.

　　超过三分之一的受访者说他们不会跑着赶公共汽车。

　　As the plane moves up, the change in air pressure reduces one third of the sensibility of our taste buds.

　　当飞机上升时,气压的变化降低了味蕾的三分之一的敏感度。