正确的表达是:
I think that it is I rather than my sister THAT / WHO AM TO BLAME FOR what has hapened.(blame)
语法:
你可以把rather than my sister当作插入语忽略掉,放在括号裏面,这样就容易理解了:
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I think that it is I (rather than my sister) THAT / WHO AM TO BLAME FOR what has hapened.(blame)