乘法和除法运算符（表 3 中列出的前四个）具有高于加法和减法的优先级。

The multiplication and division operators (the first four listed in Table 3) have higher precedence than the addition and subtraction operators.

youdao

但是，减法运算符是不可交换的；所以，需要两个操作来处理减数和被减数。

The subtract operator, however, is not commutative; therefore, you need two operations to handle the value to be subtracted and the value from which the subtraction will take place.

youdao