应该是A.
B. a tripling in the average output of ironwork was due to the replacement of charcoal by coal for the fuel used in the smelting of iron ore, in addition to several improvements in blowing machinery.
因为in addition to 前面有个逗号,所以"several...." 变成是和"a tripling"平行了,所以不对。
D. With charcoal’s being replaced ....
介词+物主代词+being done肯定错。-- by 会员 loverwy (2010/7/23 22:31:29)