这个is / was不好辨请看下面一道题：He has changed a lot. He _________ not what he _________. A. is, is B. was, was C. is, was D. was, is答案选C，上文说“他”变化很大，即“他”现在不是过去的那个样子了，故第一空填is，第二空填 was（其实第二空也可用 used to be）。请看类例：“Look! That may be the same tree that we happened to see two hours ago.” “My God. We _________ back where we _________. A. are, are B. were, were C. are, were D. were, are答案选C，We are back where we were 的意思是“我们现在又回到刚才来过的地方”。

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