问题详情：
改错：Circumstances permit, he would not have cancelled the trip he had been longing for.
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【回答】
permit→permitting 句意：如果情况允许的话，他就不会取消他一直渴望的旅行了。这里用“名词＋现在分词”构成*主格结构，相当于If circumstances permit。
知识点：非谓语动词
题型：短文改错
