根据对话内容，从下面方框中选择适当的单词填空，使对话内容完整正确。 Reporter：Can you introduce something about your latest class activity? Monitor：Sure. The students from our class planted some lines of trees on March 12 th , 2008. Reporter：How did you plant trees? Monitor：First, the students were 小题1: into groups of four. Next, each group of students planted a tree. Then, they poured some water over the trees. Reported：How do you 小题2: for the trees? Monitor： We plan to come back and look after the trees 小题3: . Reported：Sounds good. Could you tell me why you choose to do that? Monitor：As you know, pollution has become one of the most serious 小题4: . We would like to try our best to improve our environment. Reporter：Well, it’s very meaningful. If everyone can do something to protect the environment 小题5: , our city will become much more beautiful.