Look at Helen in the room.She is still working so late. 一 It _____be Helen there. She has flown to London with her parents this morning. [ ]

We should be explicit _______ the functions and benefits of the Internet, one of which is that we can also correspond _______ people in distant places.

My mother often __________ food from this restaurant.

I the camera for a week already.

Indeed,thanks to the good ideas of lots of people,like the cycling fans in the 1960s,many people around the world______the city centre streets without cars for many years