是可数名词，例如：
1.It is now possible to map the different functions of the brain.现在已有可能了解大脑的各种功能。
2.We were given a brief demonstration of the computer's functions.有人向我们简短演示了这种计算机的各种功能。
3.No computer can imitate the complex functions of the human brain.任何计算机都无法模拟人脑的复杂功能。
