— How can we finish the task in such a short time?

— Don't be worried. There ______ willing helpers. [      ]

A. were not lack of

B. are no short of

C. was no short of

D. is no lack of

实时操作系统必须在( )内完成来自外部的事件。

A．响应时间
B．周转时间
C．规定时间
D．调度时间