Many things have been done and great progress has been made in the greenization of our cities in recent years. Many trees have been planted and much care has been taken of the planted trees. But, in spite of all this, greenization in the cities in China is far from satisfactory compared with cities in other countries in the world. For example, the green space for every people in Shanghai is only 2 square meters while that of the people in London exceeds 20 square meters. We can benefit much from the greenization of our cities. First, trees absorb carbon dioxide which is harmful, but produce oxygen which is essential to human beings. Secondly, with trees all around, our cities will look more beautiful. Thirdly, trees can improve the climate of the cities, making it neither too hot in summer nor too cold in winter. Since we can get so much benefit from making our cities greener, we should spare no effort to do so. We should plant even more trees and take even better care of them while they are growing. Besides, we should not cut down trees any more. In a word, we should do everything to add to the greenization of our cities.