题目内容：

A farm planted levels or floors is called a vertical（垂直的）farm. A skyscraper type building can house a vertical farm. Since the garden is built upwards，rather than outwards，it requires much less space than a conventional farm.

The world is quickly running out of room for conventional farming. Vertical farms could be a key to this situation. An 18­story vertical farm could feed as many as 50,000 people，all in an area which is the size of the average city block. Vertical farms in the city could cut down on transportation costs as well. Think about the amount of fuel it takes to transport food from farmland to city. The resources saved would be surprising. Besides saving travel time，food would be delivered in fresher condition and with less damage.

There is a growing concern about the use of pesticides(杀虫剂) in agriculture today. But the vertical farm would be a greenhouse type environment, avoiding the need for a large number of pesticides. Vertical farms can be built in a contained space，therefore they are an excellent solution for living well in an environment far different from our own. Hydroponics(水耕法) could be a big part of vertical gardening. This would reduce the amount of soil needed to grow food. Of course，not all food does well with this type of planting，but there are many crops that actually seem to do better.

In some climates，a lack of sunlight creates a short growing season. The solar power option may not work as well here. The addition of grow lights would make it possible to grow crops in vertical gardens in these areas .In other words，we could grow crops in areas where we never could before.

Vertical farms may just be a concept for now，but they are a concept that will solve many of our problems in the future.

1.According to the passage, a vertical farm________.

A．is mainly built outwards

B．is dependent on solar power

C．is planted on levels upwards

D．is only an environmental friendly farm

2.Compared to the conventional farm, the vertical farm can________.

A．depend far less on sunlight

B．greatly increase the use of soil

C．help to protect the limited gardens

D．reduce the use of harmful pesticides

3.It can be learned from the passage that vertical farms________.

A．have been put into use

B．only use hydroponics to grow food

C．need less room than conventional farms

D．may increase the transportation costs

4.What would be the best title for the passage?

A．Vertical farms for our future

B．Ways to deal with future problems

C．Vertical farms and green skyscrapers

D．Making Full Use of Our Limited Land