Another science-based reason to focus on one thing at a time is that when you begin practising a new habit, it requires a lot of conscious effort to remember to do it.
另一个应该一次专注于一件事的科学依据是:当你开始培养一个新习惯时,需要付出大量有意识的努力,才能记得去做这件事。
主句 "Another science-based reason ... is that ..." 后接 that 表语从句;表语从句内部又嵌入 when 引导的时间状语从句 "when you begin practising a new habit";主句部分还包含形式主语 it 和后置不定式 "to remember to do it",且该不定式内部再次包含 "to do it"。因此形成从句套从句、从句套非谓语以及非谓语内部再嵌套的多重结构。