(21) put computers to practical business use, but below the surface it is the heart of an (22) - the kernel - that provides the technical wizardry to juggle multiple programs, connect to networks and store (23) .
A traditional kernel provides all the functions for applications. The kernel (24) memory, I/O devices and parcels out processor time.
The kernel also supports (25) and fault tolerance, which is the ability to recover automatically when parts of the system fail.

A．authentication

B．auto - correction

C．security

D．problem

单位工程施工组织设计的核心内容是（）

A.施工方案

B.施工进度计划

C.施工平面图

D.技术措施