当他们妈妈终于介入时，他们已经吵了一个多小时了。
They had been arguing for over an hour when their mother finally stepped in.
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had英 /hæd/|美 /hæd/
been英 /biːn/|美 /bɪn/
arguing英 /ˈɑːɡjuːɪŋ/|美 /ˈɑrɡjuɪŋ/
解释
had been arguing 是过去完成进行时，表示争吵这个动作在妈妈介入之前已经开始并持续了一个多小时。
They had been arguing for over an hour when their mother finally stepped in.
had been arguing 是过去完成进行时，表示争吵这个动作在妈妈介入之前已经开始并持续了一个多小时。