题目内容：

Going to the beach is many American’s favorite activity. They went swimming in the ocean without giving a thought to what was underwater. But those days are long gone. In the summer of 1988, many of the beaches had to be closed because garbage（废料）from hospitals was found in the water. The garbage included glass bottles with samples of blood, and people were afraid they might get AIDS from the blood. At some beaches, sewage（下水道）was found in the water. Americans were shocked by this state of affairs. People didn’t think of the underwater garbage because it was out of sight.

Some of the most polluted waters still look beautiful. San Francisco Bay is a good example of a beautiful bay that’s full of chemicals. Scientists discovered pollution in some lakes and rivers when they found fish with rotting skin. People are told not to eat too much fish because of pollution. Most American cities put their garbage in the ground. But New York and a few other cities put their garbage in the ocean. Boston Harbor is so polluted that scientists say it won’t recover until the next century. The government has ordered the city to build a sewage treatment plant, Cleaning up oceans won’t be easy, but people can no longer ignore（忽视）this challenge.

1.The main idea of the article is that _____.

A．ocean waters around America have become polluted.

B．Americans are bringing too much garbage to the beach.

C．beaches were closed because Americans were shocked.

D．going to the beach is many American’s favorite activity.

2.The oceans are polluted by _____.

A．swimmers, AIDS patients and fish.

B．Boston, San Francisco and New York only.

C．garbage, sewage and medical waste and so on.

D．swimmers and fishes

3.Many polluted waters are beautiful because _____.

A．chemicals can be beautiful.

B．they have been cleaned up.

C．pollution is underwater or hard to see.

D．there are still many fish in them

4.More people can go to the beaches near Boston if _____.

A．the city puts its garbage in the ground

B．a sewage plant is built

C．they don’t eat too much fish

D．they stop polluting the water