C选项：because of是介词，其身后的 drugs that are becoming more expensive和doctors having also written many more prescriptions for higher-cost drugs均为名词短语，这两个名词短语的核心词分别是drugs和doctors。在逻辑上，原因应该是“药物变贵”和“医生开处方”这两件事，而不是药和医生这两个名词，因此本选项是错误的。
实验开始的一个月内吸烟的青少年得抑郁症的概率是不吸烟的青少年得抑郁症概率的4倍，又因为尼古丁可以改变大脑化学物质。所以吸烟导致了青少年的抑郁症。问support
choice a, 在实验开始就已经得抑郁症的青少年，并不会比那些不得抑郁症的青少年，在实验结束之前开始吸烟。correct，排除了因果倒置
Most pre-1990 literature on businesses' use of information technology (IT)—defined as any form of computer-based information system—focused on spectacular IT successes and reflected a general optimism concerning IT's potential as a resource for creating competitive advantage
In the retail industry, for example, in which IT had been widely adopted during the 1980's, productivity (average output per hour) rose at an average annual rate of 1.1 percent between 1973 and 1989, compared with 2.4 percent in the preceding 25-year period.
retail industry的数据是作为例子跟在"productivity paradox"后面
Resource-based theory offers an answer, asserting that, in general, firms gain competitive advantages by accumulating resources that are economically valuable, relatively scarce, and not easily replicated. According to a recent study of retail firms, which confirmed that IT has become pervasive and relatively easy to acquire, IT by itself appeared to have conferred little advantage.
But some observers questioned why, if IT had conferred economic value, it did not produce direct competitive advantages for individual firms. Resource-based theory offers an answer...
一些观察质疑如果IT真的产生经济价值，为什么IT没有产生给公司直接的竞争优势。Resourece-based theoty给出了答案
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错选B，将mining和producing看作平行，将electricity看作核心词，实际上核心词应该是energy
正确选项为D，核心词为energy，用energy来发电、供热