题目内容：

Most of Bangladesh is at or below sea level. Rising seawaters linked to climate change has severely affected the country. High water from storms in coastal areas also adds salt to soil. The land is becoming salty. Crops are less productive and many areas of cropland in the country are becoming unfit for farming. These are big problems for the small country. More than 155 million people live in Bangladesh. Growing crops is the most common way Bangladeshis support themselves.

To find a way out, farmers in the country are learning to grow vegetables in so-called “vertical gardens”. The soil in these gardens is better because heavy rains have removed much of the salt.

A vertical garden is easy to make. Villagers fill containers with good soil and natural fertilizers. They put the containers on bricks so they are off the ground. They add pieces of the bricks to the soil to help water flow and drain(排水).

The farmers cut small holes into the sides of the containers. This permits vegetables with short roots a place to grow. Vegetables with long roots grow on top of the container. One bag of soil can produce up to eight kilograms of vegetables in one season.

The farmers also grow vegetables in containers made from large, thin pieces of plastic supported by bamboo. This “vertical tower” measures more than a meter wide. Each of these towers can produce more than 100 kilograms of vegetables. It costs about $12-S13 to build.

1.What is mentioned as a big problem for Bangladesh?

A. Severe climate conditions.

B. Too many people to support.

C. Lack of enough fresh water.

D. Reduced crop productivity.

2.Which mainly makes vegetable growing in vertical gardens successful?

A. Places in the soil for roots.

B. Heavy rains kept in the soil.

C. The good soil with little salt.

D. Brick pieces added to the soil.

3.What does the underlined word “they” in Paragraph 3 refer to?

A. Bricks.    B. Fertilizers.    C. Villagers.    D. Containers.

4.What can we infer about the vertical tower?

A. It is off the ground.

B. It drains very improperly.

C. It uses bamboo for containers.

D. It is unfit for growing vegetables.