Everyone has a responsibility to save _____ water, if future generations are to enjoy a similar standard of living to _____ we enjoy now.
32.Many experiments_____before the research team was able to get the exact data to carry on project.
31.Either you or on of your students________to attend the meeting that is due tomorrow.
30.When he came back, he found the bag he had________over the seat was gone.
29.What has been studied suggest that a short nap in the afternoon_______you refreshed for the next four or five hours.
28.—How about setting up an out-of-class club to share our interests and hobbies? —Great! That’s exactly what I_________.