阅读下面短文，从短文后所给的A、B、C三个选项中选出能填入相应空白处的最佳选项。

    Today is Sunday and it's Tree Planting Day. We have no 1. Our head teacher, Mr Wang 2 us to plant trees. We plant a lot of trees at the foot of the hill behind our school. It is spring now, but it is a little 3 because it is cloudy. Each of us plants three trees. Wang Hong, Zhang Jun and I are in the 4 group. I dig nine holes. Wang Hong puts the young trees into the 5 and then puts the earth back into the holes. He 6 the earth down hard with his feet several times. After that, Zhang Jun 7 nine long sticks into the earth next to the young trees and ties the young trees to the top of the sticks to 8 them straight. After planting the trees, all of us are tired. But we feel 9. We shall plant more trees to make our country more 10.