1.those _________(参加比赛的人)must be under the age of 12.2.we ha
1.those _________(参加比赛的人)must be under the age of 12.2.we have only one earth ,so we need to
1.those _________(参加比赛的人)must be under the age of 12.
2.we have only one earth ,so we need to _______(好好保护它).