D，causing和releasing的主语都是water pipe，这是不对的
E，burst和release平行

语义理解很重要：which在这不能指代整个前面的句子，所以要用causing来表状态，是heads release the water，所以要和burst一起并列！！！

不会是which，排除ABC
D中的"releasing"是the water pipes froze的伴随状语，不合句意。
洒水器爆炸然后放水才合理。

已经被冻住的水管怎么可能又洒很多水呢？只能是洒水系统才会洒水。所以D不对，因为D的逻辑主语两个半句都是“水管”

burst release是两个连贯性的动作 平行结构合理
D releasing 与 causing 平行歧义

D中的releasing...逻辑主语是前面的water pipes，暗示和froze同时发生或者间接结果
差点错选D
It indicates, implausibly, that
the pipes’ freezing directly released torrents of water after it
had also caused the sprinkler heads to burst.

我以为前面不是一个完整的句子

A选项：第二个which用法不正确；
B选项：两个动作caused...和released...的关系是前者引起后者，而本题用and连接表示并列了；
C选项：两个句子之间仅仅用逗号隔开，不和语法；
D选项：同B选项的错误，本选项中结构默认the freezing of the water pipes是causing 和releasing的主语，而then把这两个事情分开，让两件事情有个先后顺序；
E选项：两个动词并列，表示同时发生；

pipes froze引起水管崩裂，动作引起的结果 ，需要用状语从句，排除ABC。releasing 和causing 并列表示同为froze的结果，而froze不能发出releasing。应该为the heads of the sprinkler system发出。所以，排除D。

which 只能引导定语从句。

1）Sequences of actions are normally in parallel. If two description happened at the same time, they shouldn't be parallel. Instead, use "comma + ing" to modify.
2）", then ing…" is NOT right, because the action of "comma + ing" is in the same time-frame as the main verb.

burst 和 release并列，and暗示了先后关系，先爆破再释放

解释D：A situation cannot be releasing torrents of water. Thus, the second present participle makes the sequence illogical. (Furthermore, even if RELEASING were logical, it would have to be connected to CAUSING by AND, and there is no AND.) E：to burst and release 平行

为什么最后一个选项这里用release, 而不是released。 为什么第四个选项不对