They may have been（ thinking ）about their work all day.这是做的首字母,为啥要填think的ing形式.
问题描述：
They may have been（ thinking ）about their work all day.这是做的首字母,为啥要填think的ing形式.
答
have been doing 是现在完成进行时, 表示动作从过去到现在一直在进行,而且还会进行下去
They may have been（ thinking ）about their work all day.
他们可能已经思考了他们的工作一整天 （而且还会继续思考下去）
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