设SP=2000H，AX=3000H，BX=5000H，执行下列片段程序后，问SP=？AX=？BX=？ PUSH  AX    ；SP ← SP - 2 = 1FFEH，AX=3000H  PUSH  BX    ；SP ← SP - 2 = 1FFCH，BX=5000H  POP   AX ；SP ← SP + 2 = 1FFEH，AX=5000H