The question has been raised at the meeting_____ each member country should equally share the expense of the committee. [ ]

There was something wrong with the network， or the e-mail____ earlier.

Daily print newspaper circulation had ______ by about 2%, dropping from 528 million in 2016 to 519 million in 2017.

Listen! Peter is singing in the classroom!—It _____ be him. He has gone back to his hometown.

(2013·辽宁六校高三联考)Have you ever seen any trees ________ leaves were black because of the polluted air?