A:to work
B:to be working
C:to have worked
D:to have been working
中国近代某企业“仅有丝车一百零四部,各项机械均自意、法等国。……斯时运用缫丝机械尚无相当人才,乃延意麦登斯为工程师,指导常务且所有产品需运往国外市场。自光绪八年到十三年,营业失败。”该企业出现这种结局的主要原因在于( )