OG211--不一样的问题，能否解释一下如何找寻句子主语

211. The period when the great painted caves at Lascaux and Altamira were occupied by Upper Paleolithic people has been established by carbon-14 dating, but what is much more difficult to determine are the reason for their decoration, the use to which primitive people put the caves, and the meaning of the magnificently depicted animals.

(A)  has been established by carbon-14 dating, but what is much more difficult to determine are

(B)  has been established by carbon-14 dating, but what is much more difficult to determine is

(C)  have been established by carbon-14 dating, but what is much more difficult to determine is

(D)  have been established by carbon-14 dating, but what is much more difficult to determine are

(E)   are established by carbon-14 dating, but that which is much more difficult to determine is

我查看了以前的讨论稿，大家普遍感到困惑的是对what 句子后面用is 还是are有争议。对这一点，我已经比较清楚了。但是我发现自己的问题出在对主语的判断上面。这已经影响我做题目的正确率。

比如说211题，我觉得the great painted caves 才been established by carbon-14 dating得主语。当然在看了答案之后自然觉得说不通，但是为什么总是会这样选择错了了？能请那位NN给讲解讲解吗

我觉得是不是ＭＭ看句子还不够仔细，the great paited caves后最近的动词是were occupied啊，ＭＭ怎能忽略了

谢谢猫猫，我就是看到了were occupied所以才觉得 the great paited caves是主语。如果是the period不就应该是用单数吗？

我可能装到牛角尖了，希望楼上的还有nn们拉我一把呀

句子结构提出来是这样子的the period when caves were occupied has been established.斜体部分是个从句修饰the period.

不知MM明白了吗？

哦，原来如此。我怎么这么糊涂呢？太感谢猫猫了

我试着把我的理解说出来。

The period when the great painted caves at Lascaux and LACE w:st="on">AltamiraLACE> were occupied by Upper Paleolithic people has been established by carbon-14 dating, but what is much more difficult to determine is the reason for their decoration, the use to which primitive people put the caves, and the meaning of the magnificently depicted animals.

when 引导的是一个状语，修饰the period。而句子的结构是The period has been established.

那是不是可以这么总结找主语的方法：首先看when, what引导的句子是修饰那个名词，然后再判断谓语动词的情况。或者是说，在清楚的知道状语或者是后置定语之后，直接跳到下一动词看是否和主语一致呢？

個人覺得,樓上說的很不錯!

首先,要判斷主語,必須先了解哪些是修飾語,基本有九大修飾語

查文法書皆可知悉,先把非必要的元素認清楚省略不看,才能了解S到底躲在哪?  

任何再複雜句子不外乎 S + V + 連詞 + S + V 或是省略連詞,使前or 後完整句子變成不完整句子(另一種修飾語)

任何修飾語都要殺掉,才能看出倒裝或主語的位置

這功夫不難學,每一題都問自己哪個是S 哪個是V 然後看討論帖確認 ...

時時培養這問題意識,應該這問題就不會使你困擾 ...   

像你提的 OG 211 what is  or what are ?

個人以為都有可能,不過還是以what is 為佳

理由:  A is B    A就是B  所以AB數量依"常理" 為同數量之名詞(我可沒說一定...)

題目中名詞子句的 what  ......the reason 沒畫線部份一定正確;

what 名詞子句=the reason

推定what子句其為單數名詞 故選what is ...

chenfruit說的不錯, 感谢!