英文文法to與that 請教高手

people's excessive concern for money can explain most of the world's problems.

excessive與concern之間是否有省略that
還有如果有that這關係代名詞是因為有2ㄍ動詞
那可以+to取代that嗎
如果不能 why~?
可以的話舉ㄍ例來看看!!
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4 個解答 4