Example 2：One of the environmental problems that we found is deforesting（砍伐森林）.

Huge amounts of trees have been cut down in order to provide food for the world's growing population. This is the biggest reason why mankind cut down the trees.

But we don’t know the trees are very important to the ecosystem. The loss of trees upsets the ecosystem as trees are necessary to build topsoil, maintain rainfall in dry climates, purify（使某物纯净，净化） underground water and convert CO2 to O2. Trees bring water up from the ground, allowing water to evaporate（蒸发）into the atmosphere. The evaporate water then returns as rain, which is vital to areas that are naturally dry. Trees can also obstruct（阻碍、阻挡）the wind. Unfortunately, as trees have been cut down, the wind has blown away the soil, leaving the land barren（贫瘠的）. The earth is left with fewer plants to breathe in the CO2. So global warming is coming.

Therefore, we need to plant more trees while avoiding deforesting. The more trees, the better.

Brief Comment: Example 1回答了当今的水污染问题；Example 2回答的是乱砍伐树木的 问题。两位考生的用词都比较得当、思路开阔，但缺点是回答得不够全面，没有完全按照题目的要求发散。

新形态2021