It's not how long you sit there with the books open; it's what you do while you're sitting.
本句式省略了一些成分,句子完整的主体结构为it's not …that matters; it's …that matters. 对两个事物进行比较时可采用该句式,强调的重点在后半句.
Once the books are open or the computer is booted up, phone calls go unanswered , TV shows unwatched, snacks ignored.
这个句子的后半部分采用了三个并列的小句phone calls unanswered, Tv shows unwatched, snacks ignored,注意到后面两个都省略动词go.当动词一致的时候,为了句子的简洁和精炼,往往可以将该动词省去,也叫承前省略.Boot up此处意为"启动".