In late 1997, the chambers inside the pyramid of the Pharaoh Menkaure at Giza were closed to visitors for cleaning and repair due to moisture exhaled by tourists, which raised its humidity to such levels so that salt from the stone was crystallizing and fungus was growing on the walls. A. due to moisture exhaled by tourists, which raised its humidity to such levels so that salt from the stone was crystallizing B. due to moisture that tourists had exhaled, thereby raising its humidity to such levels that salt from the stone would crystallize C. because tourists were exhaling moisture, which had raised the humidity within them to levels such that salt from the stone would crystallize D. because of moisture that was exhaled by tourists raising the humidity within them to levels so high as to make the salt from the stone crystallize E. because moisture exhaled by tourists had raised the humidity within them to such levels that salt from the stone was crystallizing
E. Correct. 语法笔记解释是： humidity within them...tourists身体里面不可能包含有humidity，而且by tourists在从句的介宾短语里，是不会被指代的，所以them不会指代混乱。
From the bark of the paper birch tree the Menomini crafted a canoeabout 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 yet was so light that a person could easily portage it around impeding rapids 这句话的which离其所应该修饰的核心词canoe很远，中间隔了一个插入语，还隔了个介词结构about…，但只要知道核心词是canoe就能一目了然找到which应该指的是什么。这里不能修饰紧邻的名词cedar。
Emily Dickinson's lettersto Susan Huntington Dickinson, which were written over a period beginning a few years before Susan's marriage to Emily's brother and ending shortly before Emily's death in 1886,outnumber her letters to anyone else. 这句话的which不能修饰其紧邻的名词Susan Huntington Dickinson，必须跳过介词结构to…，修饰核心词letter。
Unlike most other mergersin the utility industry, which have been driven by the need to save money and extend companies’ service areas, the merger of the nation’s leading gas company and leading electric company is intended to create a huge network for marketing the utilities in question as states open their utility markets to competition. 这句话的which不能修饰其紧邻的名词utility industry，必须跳过介词结构in…，修饰核心词merger。
In order to protect English manufacturers of woolen goods against both American and Irish competition, England passed the Woolens Actof 1698, which prohibited the export of woolen cloth beyond a colony's borders. 这里的which不能修饰紧邻的1698，必须跳过介词结构of 1968修饰前面的核心词act。
有人这里会说这不是A of B，which吗？which应该紧邻修饰啊？其实不然，因为of 1968和前面的那些A of B实际上用法不一样，这里是表示时间而不是“从属关系”。这个时间应该归在介词结构一类，所以要跳过。
Originally developed for detecting air pollutants, a technique called proton-induced X-ray emission, which can quickly analyze the chemical elements in almost any substance without destroying it, is finding uses in medicine, archaeology, and criminology. 这句话的which不能修饰其紧邻的名词emission，必须跳过分词修饰结构called …，修饰核心词technique。
