Acemoglu, 57, and Johnson, 61, are both professors at the Massachusetts Institute of Technology, in Cambridge, in the US. Together, they co-authored a book last year.
这里用了2个介词短语in Cambridge, in the US,这种结构里in the US是修饰Cambridge还是前面的Institute?
Together就用了逗号,那together是修饰整个句子还是谓语动词?