这两种情况下，只要页计数器的值在起始页和结束页之间这一条件保持为真，selpg就会输出文本(逐行或逐字)。

In either case, as long as the condition that the page counter value is between the start and end pages holds true, it outputs the text (by line or by char).

youdao

当那个条件为假(也就是说，页计数器的值小于起始页或大于结束页)时，则selpg不再写任何输出。

When that condition is false, that is, the page counter is either less than the start page or greater than the end page, it does not write any output.

youdao