A group operation does not have any effect on higher-level operations but rather affects only lower-level groups and expressions, including their brackets and super-/subscripts. For example, &quot; a + size *2 (b * size -8 c_1)^2 &quot;
组合操作并不作用于其上一层的组合，而只是针对其下层的组合和表达式，其中也包括它们的括号和上/下标，参见 &quot; a + size *2 (b * size -8 c_1)^2 &quot;