What did you do with those books given by the volunteers

Listen! Is that Millie playing the piano in the room— No, It_____ be Millie, she has gone to London.

One of the tourists ______ from the tour group. That was why the tour guide lost his temper.

Mr. Brown wants to know your name. Please _____ on the paper.

One of the most important problems we willhave to solve is ____of students’ learning method