AB；as large as，不可以少一个as
C：插入语拿去，circling紧跟planets

C: In the past several years, astronomers have detected more than 80 massive planets, most of them at least as large as Jupiter, circling other stars.

因为中间有个插入语 ( , most of them at least as large as Jupiter, )，如果去掉插入语，circling就是紧跟在planets后面修饰planets, 就可以写成astronomers have detected more than 80 massive planets circling other stars

所以 circling other stars就成修饰宾语planets了。

C: most of them at least as large as Jupiter, circling ....
可以看成是省略了being的独立主格，做伴随状语。那么因此circling的主语就是most of them，而不是Jupiter

mostly 为副词，变成修饰Detected, 语义不通。D项which circle，因为是非限定性定从需要紧跟被修饰的名词，所以变成修饰Jupiter, 那就应该是which circles.

C中circiling不能理解未状语，不然逻辑主语就不对了，之前说错了，我觉得可能问题就出在mostly，可是Mostly也有绝大多数的意思的呀

这里应该考的是定状的区别，D选项是定语从句，但是非限是修饰名词的本质特征的，这里用状语更加的合适。

老师，B选项，抛开as large as这个错误不谈，能不能看成独立主格，省略了两个be。 第一遍做的时候就是这样很自信地选错了

(2) the modifier is to be taken as "comma + -ing", a construction that modifies the preceding clause. this is the source of the aforementioned ambiguity.

ron证实了我的观点：in other words, if you introduce that sort of construction, there are now 2 ways to interpret the sentence: (1) the intended interpretation: the modifier, which is set off by commas, is to be neglected in the interpretation of the sentence, and "circling" is to be taken as if it followed "planets" immediately, without a comma (because that's the way it would be if the modifier were removed - neither of the commas would be there anymore).

下面是引用别人的，我个人认为这个circling是现在分词做后置定语修饰planet，most of them at least as large as Jupiter可以看做是个插入语，可以不看做句中成分

D.E，mostly作为副词，“主要地，通常地，多半地”，prep07上的解释是修饰错误，以为副词不能修饰名词
C.circling在这里不存在伴随的歧义，伴随一般是指伴随动作，因为本句唯一的句子是天文学家detected...，若认为伴随是不可的，逻辑主语就成了astronomers，逻辑错误；此处circling作定语修饰Jupiter.
另外可用固定搭配排除，as large as or larger than = at least as large as

clause1+clause2,Ving，这个Ving一般修饰clause2.

感觉这道题蛮坏的。。。开始我认为A和C没有区别，但是后来我发现了，A的 “, which“结构可以被看做是jupiter的非限制性定语从句！而circling这里则没有引导词带来的尴尬，去掉了同位语之后就是planets circling xxxxxxx。虽然A按照这个思路想也是对的，但是有上面说的非限制性定从的可能性所以有点模棱两可。老师看看对不对。

这个题为啥不用 most of which 尼？