对于这几个句子存在疑惑，急求解答！！！下周考试，心情你懂的

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1.Scholars who once thought Native American literatures were solely oral narratives recorded by missionaries or anthropologists now understand this body of work to consist of both oral literatures and the written works of Native American authors, who have been publishing since 1772.
Scholars who once thought [Native American literatures were solely oral narratives]是宾语从句还是定语从句？可以省略that?

2.After several years of rapid growth, the health care company became one of the largest health care providers in the metropolitan area, but then（省略it） proved unable to handle the increase in business, falling months behind in paying doctors and hospitals.
1.    该答案解释说but后面本来是应该加句子的，但是在主语相同的情况下可以省略主语。
2.    但是Manhattan教材上说：A, and B 正确，尤其是当A、B是两个较长的或独立的句子时。但注意当A、B应是两个结构完整的句子：eg1.   N v1..., and v2....错误。 Eg2. N v1... and v2....正确。  Eg3. N v1...., and he v2..... 正确
那and/but 连接两个句子， 主语相同时，第二个什么时候省略？

3.    错误的句子：Small mills have been able to put capital into new technology and remained economically viable.
解释说（好像是OG的）：remained既不能和put平行，也不能和have been able to 平行。
但两个平行的过去分词可以共享同一个助动词have。 Eg. few people have significantly reduced the amount of driving they do or made fuel efficiency a priority when shopping for cars. (GWD-12-Q13)
那这个错误的句子为什么不能remained也共享助动词have？

4.    正确句子：Pioneered by scientists at Los ...Laboratoratory, BEAM robots are not programmed to walk; instead they use brainlike circuits called neural networks to learn to walk through trial and error

;后面的那个分句主语是they,而前面的那个分句里面有两个复数名词，scientists和robots，这不算指代不清么？
是不是因为如果前面有两个语法上都可指代的名词，但只有一个逻辑意义上合理，就可以？
这种类型的句子也见过好多。。。


谢谢各位！！！！

redparade

redparade

木有人说话么？？？？