1．Last Monday the teachers and students held a grand ceremony in ________(celebrate) of the 80th anniversary of our school.
[答案] celebration
2．The factory used 65 percent of the raw materials, the rest of ________ were saved for other purposes.
[答案] which
3．It is reported that some dangerous animals were found ________(hide) in a big cave in the mountain.
[答案] hidden
4．Parents hope that their children can be educated in a ________(relax) and active atmosphere.
[答案] relaxing
