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题库 / GMATLA-SC-116
Researchers have announced that the magnetic fields emitted by one manufacturer's security surveillance system, of which type there are 200,000 worldwide, can interfere with pacemakers and that this interaction can bring on missed or irregular heartbeats, nausea, breathlessness, dizziness, and even fainting.
of which type there are 200,000 worldwide, can interfere with pacemakers and that
of which, worldwide, there are 200,000 of that type, and which can interfere with pacemakers, and
of which type there are 200,000 worldwide, they can interfere with pacemakers and
200,000 of which type exist worldwide, interfering with pacemakers, and
200,000 of that type existing worldwide and can interfere with pacemakers, and
题目分析：
本题比较长，只要能把主干找对基本上就能从容解出本题。本题主干为：
Researchers have announced that…and that…
选项分析：
A选项：Correct. 本选项在语法和逻辑上均是正确的。of which type there are 200,000 worldwide是同位语，同位于the magnetic fields。这里的type是倒装结构，正常语序为：
type of which there are 200,000 worldwide
of which there are 200,000 worldwide是type的定语从句，将先行词代入定语从句中则有：
there are 200,000 worldwide of the type
意为：
这种类型的磁场世界上有20000个。
B选项：并列连词and身前缺少谓语动词，即，announced的宾语从句中缺少谓语动词。
C选项：只要能正确提取主干就能发现在announce身后的第一个宾语从句中已经有了主语the magnetic fields，而本选项中又给出了一个完整的they can interfere with pacemakers，多了一个主语。
D选项：并列连词and身前缺少谓语动词错误同选项(B)。
E选项：并列连词and身前缺少谓语动词错误同选项(B)。
there are 200,000 worldwide of the type
C错误，双主语或者说是没有连词
of that type there are 200000 worldwide,在这种型号里，全世界范围有20万台；
如：In Country X, of the population 65 years old or older, 20 percent of the men and 10 percent of the women are employed.
C- they can't refer to security surveillance system, wrong.
①注意中间长长的插入语
②修饰很难懂的时候就不要去强行理解修饰的意思 抓住主干
做的时候只想到了C选项里they指代的是magnetic fields，但是其实这里指向的是researchers。。。