Executives and federal officials say that the use of crack and cocaine is growing rapidly among workers, significantly compounding the effects of drug and alcohol abuse, which already are a cost to business of more than $100 billion a year.
From the bark of the paper birch tree the Menomini crafted a canoe about twenty feet long and two feet wide, with small ribs and rails of cedar, which could carry four persons or eight hundred pounds of baggage so light that a person could easily portage it around impeding rapids.
逻辑上来看确实是 which 指代的 canoe. GMAT规定的 which 只指代前面的词 如: Ron always changes his mind, which makes me angry.指代的是mind 若要表示整件事则用伴随状态 ----- ······,which making me angry. 但OG上也遇到过一个题: Executives and federal officials say that the use of crack and cocaine is growing rapidly among workers, (significantly compounding the effects of drug and alcohol abuse, which already are a cost to business of) more than $100 billion a year.
(A) significantly compounding the effects of drug and alcohol abuse, which already are a cost to business of
(B) significantly compounding the effects of drug and alcohol abuse, which already cost business
(C) significantly compounding the effects of drug and alcohol abuse, already with business costs of
(D) significant in compounding the effects of drug and alcohol abuse, and already costing business
(E) significant in compounding the effects of drug and alcohol abuse, and already costs business 答案选择B。 这题中的which 指代的是 the effects when you have "X of Y" before a modifier of this type, the modifier could potentially refer either to "Y" by itself or to the whole unit "X of Y". It's up to context to determine which. 这个是manhattan 的解释 个人见解是用排除来看 逻辑错误>语法错误 有不对的地方希望大家指正~~~