11. Based on accounts of various ancient writers, scholars have painted a sketchy picture of the activities of an all-female cult that, perhaps as early as the sixth century B.C., worshipped a goddess known in Latin as Bona Dea, "the good goddess."
A. Based on accounts of various ancient writers
B. Basing it on various ancient writers' accounts
C. With accounts of various ancient writers used for a basis
D. By the accounts of various ancient writers they used
E. Using accounts of various ancient writers

1  句首的修饰结构要考虑修饰结构的逻辑和意思上的合理性：分词做句首的修饰结构，其逻辑主语指向后面的句子主语。此时要考虑是否合理，可将前面的修饰结构还原来判断。 ===》 scholar were based on accounts of various ancient writers 不合理

2  词法： Based on….  通常 GMAT中 Base 都使用被动态， based on.

3  代词指代不明确： B 中的 it scholars base it(意思为their painting work)on various ancient writers' accounts,如果指a sketchy picture意思不太对,所以不知道it指谁。
代词总的来讲应根据逻辑意思决定指代对象. 象OG11里的they若根据逻辑来判断, 有明确的指代对象, 即主句的主语. 但当ETS要说一个选项是错的时候, 即使逻辑意思清楚, 也被认作指代模糊. 所以完全依靠代词指代模糊来决定答案不可取. 一般我只把它作为最后一招. 有其他区别就先看其他区别.

但有三个代词指代的错误, ETS认为必错
1. 单复数不一致. 如用they指代a person
2. 在同一句句子中, 同一个代词指代不同的东西. (OG12)
3. 代词指代所有格, 而不是中心词. (OG90)
4  简洁：C 中 with accounts of  和 used for a basis 语意重复。 D 中 they used 修饰不明确，也不合理，不简洁。with + n. 在句首表示physically拥有, 相比之下, with更强调一种状态. 而base, compare to这类分词省略形式是应该用被动的.ETS其实偏向主动句, 因为它强调了动作发出者.