听对话,回答问题。 1. How many trees are going to be planted today? A. 700. B. 1400. C. 2000. 2. What does the speaker advise volunteers to do? A. To leam some tree-planting skills. B. To come along any time they like. C. To bring along their gloves. 3. What is the main purpose of the event? A. To increase people' s sense of environment protection. B. To invite people to join an environmental organization. C. To persuade families to have an outing in the mountains.