15. 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

1. distinguish 的用法（from, between ） （考点就是distinguish，一级排除A,B,D,E）
（常与from连用）使别于；有…特点
distinguish somebody/something from
a method of distinguishing cancer cells from normal tissue
(用from的时候要小心，分辨两个的话优先用distinguish between  and)
distinguish between A and B . A/B 不同范畴进行区分。Between 不能省略,distinguish between A and B .which.  which 很清晰指向B. 
distinguish A and B .which.  which 可能指向 A and Ｂ或者 B ,不清晰
Distinguish A from B  A 是 B 的子集，从Ｂ中把A 挑出来。

此题是把假的病症和真的病症区分开, 不是把假的病症从真的病症里面区分出来) 

2. 情态动词要保持： may 不应该改成 perhaps. 

3 代词：mood swings, which may be violent without their being grounded          Their 多余