When entering information manually in the Commands window, please note that a number of operators require spaces between the elements for the correct structure. This is especially true if you are using values instead of placeholders in your operators, for example, to construct a division 4 div 3 or a div b.
在“命令”窗口中手动输入时应注意，对于很多运算符而言，空格符是对保证结构的正确必不可少的。尤其是当您用数值代替占位符时，例如，建立除式 4 div 3 或 a div b 时。