一道英语名词用法方面的题,

一道英语名词用法方面的题,
computers can do _______ work in a short time,but a man can do ____by himself.
有两个选项A.a great deal of; much
B.much; a great deal
就我个人看来,a great deal of 修饰不可数名词,既可以用作a great deal of work,a great deal work,而deal 本身作为一个名词,第二个空的do这里也可以当宾语,也就是do a great deal,当然,much也可以作代词当do 的宾语．因此这两个选项我觉得都可以,可是标准答案是给的B!