China began to open to the outside world in the late 1970s._________, there have been great changes in the country.
Jack’s room is dirty. It should _________ right away.
Please remember _________ your homework to school.
When we feel tired, we keep our eyes _________.
The apple pie tastes good. Can I have _______ one?
Three tall boys sit in front of me so I ________ see the blackboard.