题目原文：
The sea otter is a small mammal that lives in waters along the western coast of North America from California to Alaska. When some sea otter populations off the Alaskan coast started rapidly declining a few years ago, it caused much concern because sea otters play an important ecological role in the coastal ecosystem. Experts started investigating the cause of the decline and quickly realized that there were two possible explanations: environmental pollution or attacks by predators. Initially, the pollution hypothesis seemed the more likely of the two.
The first reason why pollution seemed the more likely cause was that there were known sources of it along the Alaskan coast, such as oil rigs and other sources of industrial chemical pollution. Water samples from the area revealed increased levels of chemicals that could decrease the otters’ resistance to life-threatening infections and thus could indirectly cause their deaths.
Second, other sea mammals such as seals and sea lions along the Alaskan coast were also declining, indicating that whatever had endangered the otters was affecting other sea mammals as well. This fact again pointed to environmental pollution, since it usually affects the entire ecosystem rather than a single species. Only widely occurring predators, such as the orca (a large predatory whale), could have the same effect, but orcas prefer to hunt much larger prey, such as other whales.
Third, scientists believed that the pollution hypothesis could also explain the uneven pattern of otter decline: at some Alaskan locations the otter populations declined greatly, while at others they remained stable. Some experts explained these observations by suggesting that ocean currents or other environmental factors may have created uneven concentrations of pollutants along the coast.
题目音频：
学术写作
简化大意：
教授：大学毕业后，是继续全日制读书还是边工作边学习？
Andrew：全日制读书（类似读研），因为太累很难平衡
Claire：边工作边读书，可以学到更多
详细题目回忆：
Doctor Diaz:
As you approach graduation, you may be considering your next steps for further education. Some opt to enroll full-time to complete an advanced degree as quickly as possible. Others choose to work while slowly progressing towards a degree. Given these options, I’m curious to know your thoughts. After finishing your undergraduate studies, do you prefer pursuing an advanced degree full-time or continuing work while studying part-time?
Andrew:
I think it’s better to go to college full-time instead of trying to balance part-time classes and a full-time job. For me, I know I wouldn’t be able to focus on my studies if I was exhausted from work all the time. Full-time college allows me to put all my energy into my classes and get the most out of my education. Trying to do both college and work full-time seems way too stressful for me to handle. I’d rather get my degree done faster by being a full-time student.
Claire:
I think going to college part-time while working is better because I can use what I learn in class at my job right away. The classes feel more relevant when I’m able to apply the material to real work situations. Instead of just memorizing concepts, I get to see how they work in practice. And getting work experience while I study looks good on my resume. I think balancing the two helps me get more out of my classes and prepares me for my career at the same time. I’d rather take classes part-time and work than just study full-time.
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