Walnut trees environment stresses such as drought by producing significant amounts of a substance similar to aspirin（）

beauty and its hardwood. It is said that a single tree once sold for $11000. Hardwood hunters search the woods for trees that will bring such prices.

When the Dutch first sailed up the Hudson River 300 years ago, they discovered black walnut trees so large that the first branch was as much as 70 feet above the ground. In colonial times the black walnut became one of America's first exports, because it was highly prized by cabinetmakers. During World War I almost all natural woods of the black walnut were eliminated. Trees were harvested for gun stocks, and even the nutshells were collected to use as filtering material in gas masks.

Today, growing black walnut trees is profitable because of the demand for it. However, not every black walnut tree is necessarily valuable. It must be inspected to see if it meets certain standards. Furthermore, the roots of the black walnut tree produce a poisonous substance that will cause harm to tomatoes, potatoes, blackberries and apples.

Why is the black walnut tree so valuable7

A．Because of its hardwood and its beauty.

B．Because of its historic value.

C．Because of its great age.

D．Because of its great size.

A．By watching some films about World Environment Day.

B．By listening to some lectures and planting trees, etc.

C．By planting trees, having some green concerts, bicycle parades, etc.

D．By delivering some speeches about World Environment Day.

Which of the following is the main idea of the whole passage？

A．There are three ways in which trees are important to human beings.

B．Providing man with shelter is the most important role the trees play.

C．Supplying man the wood and warship is the most important way the trees have.

D．Assisting in stopping drought and floods is the most important role the trees play.

A．By watching some films about World Environment Day.

B．By listening to some lectures and planting trees, etc.

C．By planting trees, having some green concerts, bicycle parades, etc.

D．By delivering some speeches about World Environment Day.

A．By watching some films about World Environment Day.

B．By listening to some lectures and planting trees, etc.

C．By planting trees, having some green concerts, bicycle parades, etc.

D．By delivering some speeches about World Environment Day.

Which of the following is true in describing the black walnut tree？

A．The black walnut tree is valued for its nuts.

B．The black walnut tree is famous for its size.

C．Every walnut tree is highly valuable and profitable.

D．A single black walnut tree was once sold for $11,000.

nvironment” does not imply that ().

A、everything in the ecosystem is part of one complete whole

B、most people hold a wrong view on the environment

C、everything affects and is affected by its environment

D、people are not conscious of the importance of trees

Three fundamental aspects of (forest conversation) are the protection of immature trees, the use (of proper) harvesting methods, and (provide) for an environment (that supports) reproduction.

A．forest conversation

B．of proper

C．provide

D．that supports