观察下面句子.试着归纳其画线部分所包含的句型结构. This was a time when the two countries were at war．

观察下面句子，试着归纳其画线部分所包含的句型结构。

This was a time when the two countries were at war．

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试题答案

答案：

This was a time when…正值……时期