set talk off public val1,val2 val1 = 10 val2 = 15 do down ? val1 ? val2 release all &&只释放私有变量 display memory like val? release val1,val2 &&必须明确地释放公共变量 display memory like val? procedure down private val1 val1 = 50 val2 = 100 ? val1 ? val2 return