【推荐1】We should figure out some ways to stop people from polluting the river and call ________ them to fight against pollution. (用适当的词填空)

【推荐2】In 1995, Dr. Madan Kataria called on a group of students in a park________ (test) whether adding regular laughter to people’s lives would improve their well-being, Kataria also introduced deep breathing and simple yoga moves into the exercises.（所给词的适当形式填空）

【推荐1】Among the works _________ exhibition the visitors will find the best ones.（用适当的词填空）

【推荐2】These teams are going to try out ________ the Olympic Games. (用适当的词填空)

【推荐3】They knew about the accident. That is because they were________ the spot when it happened. （用适当的词填空）