divide sth by something:被.....分开
divide sth into: 把......分成
例句：
We will divide the students into six groups.
我们将把学生分成六组。
His study was divided from the living room by a thin wooden partition.
他的书房是用薄隔板从客厅分隔而成的。
divide the cake by a knife用刀来切蛋糕
divide the cake into four parts把蛋糕切成四份
