块表达式 L: X:y| BicPen goto: X@y] L:X:y| BicPen goto: X@y] value: 100 value: 250 BicPen goto 100@ 250 I ablock aBlock+[ This is a string' displayat: 500@ 500] Display white. aBlock value·块表达式 [:x:y｜BicPen goto：x@y] [:x:y｜BicPen goto：x@y] value：100 value：250 BicPen goto 100@ 250 ｜aBlock｜ aBlock←['This is a String' displayAt：500@ 500]. Display white. aBlock value