核心问题
So bright was the moon that flowers were bright as by day. (Mansfield) 请问这里为什么要主谓语倒装？
词典解答
按照英语惯用法，在 so...that + 结果（程度）从句这一结构里，如果充当表语的 so + 形容词或充当状语的 so + 副词放在句首，则主句的主语和谓语要进行部分倒装。例如：
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So sudden was the attack that we had no time to escape. (PEG) 袭击来得非常突然，以致我们都来不及逃跑。
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So absorbed was he that Nathalie hadn't dared to make a sound. 他是那样全神贯注，以致纳瑟莉没有敢出声。
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So simple does the trick seem that we are likely to overlook the magician's dexterity. (IME) 戏法似乎太简单, 以致于我们很有可能忽略魔术师的技巧。
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So earnestly did the boys beg that their father gave his permission. (IME) 男孩儿们恳求得如此热切,结果父亲同意了。
(参见 so )