[求助]BY语法第八章25，29题。第九章46题。section2 7题

P237.25

Sales of US manufactured goods to nonindustrialized countries rose to 167 billion in 1992, which is 14 percent more than the previous year and largely offsets weak demand from Europe and Japan.

a.which is 14 percent more than the previous year

b.14 percent higher than the previous year's figure

c.an amount that is 14 percent higher than the previous year's figure

答案c。b为什么不对？

P240.29

Presenters at the seminar , one who is blind , will demonstrate adaptive equipment that allows visually impaired people to use computers.

a.one who

b.one of whom

答案b。但是我认为whom是宾格。这里是one of Presenters is blind。不是应该用主格who吗？

P279.46

Formulas for cash flow and the ratio of debt to equity do not apply to new small businesses in the same way as they do to established big businesses , because they are growing and are seldom in equilibrium

a.Because they are growing and are seldom in equilibrium , new small businesses are not subject to the same applicability of formulas for cash flow and the ratio of debt to equity as established big businesses.

b.Because new small businesses are growing and are seldom in equilibrium , formulas for cash flow and the ratio of debt to equity do not apply to them in the same way as to established big businesses

答案是b。书上的解释是a中的are not subject to the same applicability of 不如b中的do not apply to 。但我认为b中的them的指代也不清楚啊，them 应该先指代formulas，然后再指代small businesses。若指代formulas意思就不对了。

P339.7

Migraine , the most debilitating common form of headache , afflicts perhaps 18 million Americans , who collectively lose 64 million workdays a year , and they cost the nation 50 billion in medical expenses and lost work time.

a.year and thus cost the nation 50 billion in medical expenses and lost

b.year,so as to cost the nation 50 billion in medical expenses
    and lost

答案是a。我认为who collectively lose 64 million workdays a year and thus cost the nation 50 billion in medical expenses and lost work time中，因为and thus cost 前面没有逗号，所以前面的collectively lose和cost应该的主语应该同是who，既Americans 。但Americans cost the nation 50 billion in medical expenses不对。

而b的错误在哪里？

而b的错误在哪里？

请指教，谢谢