一个关于定语从句的选择题不是很明白

superhero123

1 J8 C: }% ^. r; c1 O$ j& @: CDolphins might be trained to cooperate with fishermen and help them by finding, tracking, herding, or even catching fish — ______ activities dolphines are expert.

/ R6 X$ W0 a+ v+ r8 S$ C3 FA. at all of these
) j, s1 j; }+ G' K" r8 ^$ z  B4 dB. in all of which
C. all of which
D. in all of what

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0 b1 C+ U! p2 U) `答案是B，这个我是能理解的，
- Z8 T9 L5 `, |; G& k3 w但是关于句子结构，有一点不明白，
如果是B的话，in all of which activies ，这里为什么还会再有一个activities呢？ 关系代词which不是已经用来代替了前面所述的activities了么。
in all of which dolpines are expert 如果这是这样表达，难道不对么？
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trivialstuff

《柯林斯英语语法系列：10.限定词及数量词》

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2 ?" g; q' @4 i5 I  z! ]- q可以这么理解，如果which前面有介词，它通常可作限定词使用。
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你去哪里

7 i, `% A* a+ t4 k- s- d) q$ n徐广联《大学英语语法：讲座与测试》第五版，第十七讲：

（5）which 在定语从句中可以单独作定语……Excitement deprived me of all power of utterance，in which case I would but stand there，nodding and waving. 我激动得说不出话来，在那种情况下，我只能站在那里点着头，挥着手。（定语）
& }1 _6 z8 k! B9 k$ ^( sTen years of hard work changed her greatly，for which reason he could hardly recognize her at first sight. 10 年的辛劳使她变化很大，你一见之下很难认出她来了。（定语）
3 v( P9 T3 ]! P$ J/ D! nWater boils at 100℃，at which temperature it changes to gas. 水在 100 摄氏度沸腾，在这个温度上就变成了气体。（定语）
I called her by the wrong name, for which mistake I apologize. 我叫错了她的名字，我为这个错误而道歉。

jonah_w

Dolphins might be trained to cooperate with fishermen and help them by finding, tracking, herding, or even catching fish, in all of these activities dolphins are expert.
8 p. `* b. J: R+ {' f& V: W  F/ _  N
现在把最后一句，不要看答案，换成从句形式。

yuqinghuaz1

因为这里是对于finding, tracking, herding, or even catching fish 这些activities的补充说明，which在这里做限定词使用，表示是刚刚提到的。例如，It stormed all day,during which time the ship broke up .

eeshu

我觉得答案错了

superhero123

jonah_w 发表于 2018-11-18 13:22
- L/ a( O) R, j5 `: B5 @: eDolphins might be trained to cooperate with fishermen and help them by finding, tracking, herding, o ...

怎么换？

jonah_w

superhero123 发表于 2018-11-18 16:49
% ?! _! m8 m0 Z  U7 D怎么换？

可以看看 yuqinghuaz1 的回答，我觉得解释的比较到位。如果还看不懂，就直接记住吧。

menglongma

现在加and，把原来的句子变成and连接的并列句，就更好理解了。Dolphins might be trained to cooperate with fishermen and help them by finding, tracking, herding, or even catching fish, and  in all of these activities dolphins are expert.
# j/ \9 h  |3 w8 k' X9 u. U可是，原句没有and，后边的句子就一定是一个从句，否则就是病句。
: j6 [. e5 n& [* V$ f, G' I8 J  t/ x当然，这个句子像你所说的 Dolphins might be trained to cooperate with fishermen and help them by finding, tracking, herding, or even catching fish,  in all of which dolphins are expert. 是更常见的。这样写  Dolphins might be trained to cooperate with fishermen and help them by finding, tracking, herding, or even catching fish,  in which dolphins are expert. 也是对的。而Dolphins might be trained to cooperate with fishermen and help them by finding, tracking, herding, or even catching fish, and  in all of which activities dolphins are expert. 的意思更具体和清晰。

superhero123

trivialstuff 发表于 2018-11-18 18:42
《柯林斯英语语法系列：10.限定词及数量词》

2 T9 f2 Y+ E. d1 O: F4 v1 O/ c这个是正解了

bottomsup

还有一个问题，be expert后跟at/in都行，那A为什么错误呢？因为这里必须用从句，如果前面是句号，才能用these？

GL_n

In general, "which" can be used as determiner or pronoun. Here "which" could be regarded as a determiner. Look at this sentence: Which book are you looking for? At the same time, "which" is also a mark of starting to construct a subordinate clause.

565079101

因为这里的which是限定词