填空题 从供选择的答案中选出应填入英语文句中()的正确的答案。
Applications put computers to practical business

• (A), but below the
• (B) it's the heart of an operating system the kernel that provides the technical wizardry to juggle multiple program, connect to networks and store
• (C) .
  A traditional kernel provides all the functions for applications. The kernel
• (D) memory, I/O devices and parcels out processor time.
  The kernel also supports security and fault
• (E), which is the ability to recover automatically when parts of the system fail.
  A: ① used ② use ③ apply ④ applied
  B: ① earth ② bottom ③ table ④ surface
  C: ① graphics ② data ③ text ④ image
  D: ① manages ② manage ③ managed ④ managing
  E: ① error ② question ③ tolerance ④ problem