A、To establish priorities among all tasks first. B、To allocate mental resources to different tasks. C、To supervise the preparato

(33)Researchers report that doing two or more things at once may decrease efficiency and actually take extra time switching from one task to another. In the most severe cases, it can even mean the difference between life and death.
     In the study, four groups of young adults carried out a series of tasks and switched between different tasks, some complicated, such as solving math problems, and some more familiar, such as identifying geometric shapes. (34)The researchers found that time was lost in just switching from one task to another, and that time costs increased with the complexity of the tasks. “For each aspect of human performance—perceiving, thinking and acting people have specific mental resources whose effective use requires supervision through executive mental control,” said the lead author, David Meyer in materials provided with the report.
      So-called“ multitasking” is becoming increasingly common because of cell phones and computers. the researchers point out, but it may just be adding wasted time and inefficiency to our days. A mere half second of time lost to task switching can mean the difference between life and death for a driver using a cell phone, Meyer said. (35)The authors say the research should make employers and employees think twice before implementing multitasking.