OG 11th 35题,关于and的并列.

35 Federal authorities involved in the investigation have found the local witnesses are difficult to locate, reticent, and are suspicious of strangers.
(A) the local witnesses are difficult to locate, reticent, and are
(B) local witnesses to be difficult to locate, reticent, and are
(C) that local witnesses are difficult to locate, reticent, and
(D) local witnesses are difficult to locate and reticent, and they are
(E) that local witnesses are difficult to locate and reticent, and they are

这道题（c）是正确答案，但是我很奇怪locate，reticent之间为什么没有and？他们不是并列关系吗。我的理解是这道题are difficult 和( are ) suspicious是并列的，locate , reticent是在difficult中的子并列，这个理解对吗？如果这个对，那么locate, reticent之间就应该有and,OG自己说并列的形势是x,y and z.

另外还有一个问题,诸位的题目都是自己敲上去的?还是从电子版拷贝的?我的哦OG没法拷贝好像...需要OCR一下

Federal authorities involved in the investigation have found the local witnesses are difficult to locate, reticent, and suspicious of strangers.

... are difficult/adj1 to locate, reticent/adj2, and suspicious/adj3 of strangers. = ...are adj1, adj2 and adj3.