Ⅰ.用所给词的适当形式填空
1. (erode) from winds has removed a large part of the land.
答案Erosion
2.One method of soil (conserve) is the use of windbreaks.
答案conservation
3. (substantial) evidence exists to support the theory.
答案Substantial
4.No one should break the (ecology) balance.
答案ecological
5.The roof (collapse) under the weight of snow.
答案collapsed