A、Listening to a teacher and then taking a test. B、Recording just the main points, or summarizing. C、Stopping mindless transcrip

Now listen to the following recording and answer questions 20 to 22.
    Many college students have given up taking class notes by hand. Instead, they type on laptops or tablet computers. But scientists from Princeton University and the University of California say that that method is less effective. If you need to remember something, write it.(20)Writing notes by hand is much better for long-term memory of ideas, or conceptual information. That is the finding of a 2014 study published in the journal Psychological Science. So, turn off your computer if you want to remember something. Computers can take your attention away from your work. They can be distracting. Computers provide the chance to send a quick message to a friend, check a sports’ score, shop or watch a funny cat video. It is really hard to resist a funny cat video. But scientists say computers may hurt performance in school, called academic performance. Here is what the research showed.(21)Students who type notes on a keyboard often transcribe, or write down what the professor says word-for-word. They may write without really thinking about what they are writing. These electronic notes contained more words. But scientists say it leads to mindless transcription. However, students taking notes longhand, or by writing them, need to first process the information they hear. Then they record just the main points, or summarize. They use fewer words. This is because people usually write slower than they type. This process of summarizing information leads to a deeper understanding, say the researchers. In the study, students listened to a teacher and then took a test. Some took notes by typing on a computer. The others took notes by writing them down. Both groups performed about the same in remembering facts. But students who typed their notes did much worse on conceptual questions. These questions required them to understand an idea. Those who typed also could not stop transcribing even after they were told to try to avoid it. So even if you want to stop typing what you hear word-for-word, you might not be able to. Also, researchers found that those who wrote their notes remembered conceptual information better a week later.(22)Scientists know that students probably will still use their laptops and tablets in class. But they suggest using some of the available technologies for writing notes by hand on computer screens. They say this might be a good compromise between old school and new school.
20. What is the finding of the 2014 study regarding people’s memory of something?
21. What’s the disadvantage of typing notes on a keyboard?
22. What might be a good compromise between taking notes by hand and typing on a computer, according to the scientists?