有一个句子是How can you imagine him making such a mistake?这句子对吗?不是

imagine him saying that 意思是 能想到他那样说
imagine him to be older 意思是 以为他的年龄更大一点
二者区别应该是doing 是指 能够确定是事实
to do 是指 一种猜测
imagine him making such a mistake 确定他犯了这样愚蠢的错误,就是已经发生的事实所以句子是对的,而不是to be