Select which of the following ones are research area of artificial intelligence.选择下列哪些是人工智能的研究领域
A.Distributed computing分布式计算
B.Expert system专家系统
C.Software outsourcing软件外包
D.Machine learning机器学习
E.Image understanding图像理解
F.Face recognition 人脸识别
正确答案：Expert system专家系统；Machine learning机器学习；Image understanding图像理解；Face recognition 人脸识别