难题请教。我有理由觉得答案错！

Q20:

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.

1. of which type there are 200,000 worldwide, can interfere with pacemakers and that
2. of which, worldwide, there are 200,000 of that type, and which can interfere with pacemakers, and
3. of which type there are 200,000 worldwide, they can interfere with pacemakers and
4. 200,000 of which type exist worldwide, interfering with pacemakers, and
5. 200,000 of that type existing worldwide and can interfere with pacemakers, and

答案选了D，那不是没有了谓语动词了吗？

我选了A， of  which type there are 200,000 worldwide 尽管不好，但有错吗？

Q41:

Elk now live almost solely in the Rocky Mountains, which would make it seem that elk are mountain dwellers, while they once ranged over virtually all of the continental United States except for a small strip in the extreme Southwest.

1. Elk now live almost solely in the Rocky Mountains, which would make it seem that elk are mountain dwellers, while
2. The fact that elk now live almost solely in the Rocky Mountains would make it seem that they are mountain dwellers, but
3. It would seem that elk would be mountain dwellers because of their living now solely almost in the Rocky Mountains, but still
4. Now living almost solely in the Rocky Mountains, it would seem that elk were mountain dwellers, although
5. It seems that elk would be mountain dwellers from the fact that they now live solely almost in the Rocky Mountains, since

再问一题，答案选A， 可是Which 不能指代句子阿？

我选了B。 虽然拗口，但是语法应该没错吧？

我的意见

1 D 谓语动词是bring

2 B Which 不能指代句子我也是这么认为的

to be discuss...

对于第一题，我的问题是：and前面的分句，也就是that引导的从句没有了动词（如果选所谓的答案D的话）

BZ,NN们快来回答看看，刨析一下句子结构。

第一题，楼主仔细看看D选项就发现了，其实that从句里的主语是并列的两个名词：the magnetic fields and this interaction。中间的内容全部是修饰语。两个名词共用一个谓语can bring。这个题我也做错了，看到题目就先入为主的认为是两个从句并列，结果中招了，不得不佩服出题人的阴险。

第二题，支持B，不知道为什么选A，which的错误很明显啊。

一点猜想，不一定正确：

A. Elk now live almost solely in the Rocky Mountains, which would make it seem that elk are mountain dwellers, while they once ranged over virtually all of the continental United States except for a small strip in the extreme Southwest. 

B. The fact that elk now live almost solely in the Rocky Mountains would make it seem that they are mountain dwellers, but they once ranged over virtually all of the continental United States except for a small strip in the extreme Southwest.

把答案都代入原句后发现区别不大

1. B的make it seem that后面的they是否有误指代mountains的嫌疑？相比之下，A重复了elk而没有用they。这点A优。

2. B的主句主语是the fact, 从句主语是个代词they。而A主语是Elk, 从句主语是they保持了一致。不知道这个算不算一个？

3. 还有就是A的which的问题了，但是这个不能算是一个语法错误。

4. 原文是主句一般时态，B变成了the fact would make it seem that....，变成了虚拟。这算是一个致命有效性错误。

各有问题。但都是有效性问题，不是语法错误。实在不知道是如何权衡。 open to discuss.

B的make it seem that后面的they是否有误指代mountains的嫌疑？相比之下，A重复了elk而没有用they

这个肯定不会后面一句 while
                they once ranged over virtually all of the continental United States except for a small strip in the extreme Southwest. 的they是指 Elk

那么they的指代是没有问题的这里

那么they的指代是没有问题的这里