What are the trees used___?

What are the trees used___? What are the benefits of forest trees?什么意思 the students are planting trees over there.what The trees are growing What are those?____are___apple_ trees What are trees useful for? ________are the trees?They are green.A What B What colour C what on the trees?There are many apples.空白处填is 还是are? What are they?They are____young trees. What good are trees?完成对话 关于What Good Are Trees的英文, what are___over there?they are trees.