问题描述：
以下三个句子中的介词短语分别做什么?
1.Keep on learning as long as you live活到老,学到老 2.Man’s dream of flying in space has come true人类太空飞行的梦想已变成现实 3.She left without saying goodbye to us她没有向我们告别就走了
1.Keep on learning as long as you live活到老,学到老 2.Man’s dream of flying in space has come true人类太空飞行的梦想已变成现实 3.She left without saying goodbye to us她没有向我们告别就走了
问题解答：
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