题目内容：

Josh Hill, a biology teacher at Mar Vista High School in California, US, often gets sick after swimming in the ocean at Imperial Beach in California.

He and a group of students are raising awareness(意识)about water pollution by taking weekly water samples(样本)of the ocean and publishing their results online.

Every Thursday, Hill and his students collect water from the ocean. Students then take the samples to their school and test them for levels of bacteria. Usually, samples closer to the border have higher levels of bacteria, Hill said.

“Water quality is usually the worst at the southern end and it increasingly gets better,” he said.

Hill collects the samples on Thursdays so that students can publish the results on the Surfrider Foundation’s website in time for the weekend. The Surfrider Foundation has give Mar Vista lab equipment and promote the students’ results on its site.

Most of Hill’s students grew up in Imperial Beach. Many have gotten sick from the water or know someone who has.

Cameron Bell, 17, who is currently applying to college, wants to pursue a STEM career. He appreciates the fact the he can get lab experience at school. “Our research really impacts our community because it’s keeping people safe,” he said.

On a recent Thursday morning, Anthony Gass, 15, collected some samples. Before he got into the water, his classmates helped him put on waterproof(防水的)clothes and tie a rope around his waist to protect him from the onrush of water.

Hill said the protection probably wasn’t necessary, but that it was better to be safe than to be sorry. “We just want to make sure we protect the students,” he said.

1.What did Josh Hill and his students discover after checking the water samples?

A. Water quality at the northern end isn’t poluted.

B. Water nearer to the border is bless polluted.

C. Water pollution is getting worse and worse.

D. Different levels of bacteria are found in the water.

2.What can we learn about Bell?

A. He is now applying for a job in college.    B. He doesn’t want to have a career in STEM.

C. He thinks that their research is meaningful.    D. He isn’t grateful for his research experience.

3.According to the passage, which of the following is TRUE?

A. The results of the students’ research are not published online.

B. Many students in Imperial Beach get sick due to the water pollution.

C. Very few safety measures are adopted in students’ research work.

D. Mar Vista High School is not equipped with modern science labs.

4.What is the passage mainly about?

A. US students’ research on water pollution.    B. Severe ocean water pollution in the US.

C. US students’ tests for water resources.    D. Tips on how to reduce water pollution.