其实，做梦不仅是一种正常的心理现象，而且是大脑的一种工作方式，有助于记忆、过滤无用信息，保证正常的效能。

Actually, the dream is not only a normal psychological phenomenon, and is one of the brain's a way of working, help to memory, filter useless information to ensure the normal performance.

youdao

进行设备大修理的经济性分析、论证工作，可以提高计划的正确性和工作效率，减少许多无用功劳动和浪费现象。

The economic analysis and demonstration on overhaul of equipment can improve the plan and efficiency of work, and reduce useless work wasting time.

youdao

不客气地说，大量攻略严重存在时间后滞现象，同样也介于有用无用之间。

Let's put it in a more direct way: since most of specific methods have time lag, they can be between being useful and being not.

youdao