请教一个基本语法，现在分词的被动形式being done，og11-107

不好意思，请问一下，这里面being grounded该怎么理解？

好像听说GMAT里面一般出现了being，大部分是错的，因为累赘。

这里面用grounded替代它不行吗？

107. In his research paper, Dr. Frosh, medical director of the Payne Whitney Clinic, distinguishes mood
                swings, which may be violent without their being
                grounded in mental disease, from genuine manic-depressive psychosis.

(A)         mood swings, which may be violent without .

their being grounded in mental disease,

from genuine manic-depressive psychosis

(B)         mood swings, perhaps violent without being

grounded in mental disease, and genuine

manic-depressive psychosis

(C)        between mood swings, which may be violent

without being grounded in mental disease,

and genuine manic-depressive psychosis

(D)        between mood swings, perhaps violent

without being grounded in mental disease,

from genuine manic-depressive psychosis

(E)         genuine manic-depressive psychosis and

mood swings, which may be violent

without being grounded in mental disease

Idiom + Rhetorical construction

This sentence contrasts two problems, and it must use the correct idiomatic expression to do so clearly and effectively: Dr. Frosh distinguishes between

x (mood swings) and y (psychosis). The clause that describes mood swings (which may...) should be as clear and concise as possible; the possessive pronoun their is awkward and should be omitted.

A       Fails to use the correct idiomatic expression; their should be omitted

B        Incorrect idiomatic expression; the phrase perhaps violent ... is awkward and unclear

D       Idiom incorrectly formulated as distinguishes between x fi-ons y; the phrase
                perhaps violent ... is awkward and unclear

E       The preposition between has been omitted from the idiom

The correct answer is C.