Sometimes you need to group sub-expressions with parenthesis, but don't want the parenthesis to spit out another marked sub-expression, in this case a non-marking parenthesis ?

有些时候你需要使用圆括号对子表达式分组，但是却不想这个括号里面的内容再作为标示子表达式，在这种情况下可使用非标示圆括号？

And marking a book is literally an expression of your differences.

而在书上作记号，实际上就是表达你赞同或不赞同。

The epigenome is a molecular marking system that controls gene expression without altering the DNA sequence.

表观基因是在不改变DNA序列的前提下控制基因表达的分子标记系统。