多项选择题
A.mapPartitions B.lookup C.mapPartitionsWithIndex D.count
A.宽依赖 B.窄依赖 C.分区关系 D.继承关系
A."Hello"(0),"Hello"(5) B."Hello".take(1),"Hello".reverse(0) C."Hello"(1),"Hello"(5) D."Hello".take(0), "Hello".takeRight(1)