[填空题]Since rainforest bacteria and trees depend on cacti other for life, the relationship they form is termed______.

[填空题]Since rainforest bacteria and trees depend on cacti other for life, the relationship they form is termed______.

[填空题]Since rainforest bacteria and trees depend on each other for life, the relationship they from is termed ______.

[单项选择]Since the earliest times, trees have always been very useful and important to man who made use of them in numerous (众多的) ways for his daily life. Even today trees continue to serve man in so many useful ways.
Trees provide man with food, fuel for burning and building material in the form of wood. Without trees it would be impossible to build houses, boats and even bridges. Furniture such as tables, chairs and cupboards are also made from wood.
In the tropics (热带) where it is very warm throughout the year, trees protect man from the fierce heat of the sun. They are useful in preventing good and fertile top soil from being washed away during heavy rains which are so common in the tropics.
If there are no trees or vegetation (植物) of some sort to hold back the soil with their roots, heavy rains would wash away the rich surface soil so essential for agriculture. The result is that the land becomes useless and unproductive.
There are many desert areas in the world. A long
A. early man did not know how to make use of trees
B. trees are not as useful now as they were in the past
C. trees were more useful in the past than they are now
D. men have always found trees useful

[单项选择]He______two thousand trees since 2001.
[A] planted [B] has planted [C] will plant

[单项选择]

Healthy trees are important to us all. Trees provide shade, beauty, and homes for wildlife. Trees give us products like paper and wood. Trees can give us all these only if they are healthy. They must be well cared for to remain healthy.
Your trees’ trouble may be you yourself. People spend much time and money to plant and maintain trees. Trees improve the looks of homes, parks, business, and public buildings. Yet, people who love trees the most may be the ones who cause them injury. Of course, they do not do this on purpose. They are most likely not aware of the kinds of things that injure trees. There are many people-caused tree injuries. You should become aware of them and avoid them. Learn the things that can help to keep your trees healthy.
Healthy trees are beautiful. They make our world a pleasant place to live ill. Unhealthy trees are not as beautiful. They make our world less pleasant. Healthy trees help to cool and clean the air. They can even deade
A. never cause trees injury.
B. damage trees on purpose
C. do some harm to trees without knowing it
D. not be aware of which trees are healthy