Why do humans prefer some smells over others? One theory, increasingly     1       (support) by experts, suggests that smell preferences are learned. It’s easy to explain how we determine     2     smells are dangerous or not: we learn. This has been adopted to ensure easier detection of gas leaks. Gas naturally     3     (have) no recognisable smell. However, a strong smell is added so that we can raise the alarm when we detect the smell associated with danger.

3 . Music has long been considered to be an enjoyable pastime for many people．     1     The mental health benefits from music can't be argued．Music could also be helping you with many other health problems behind the scenes．

    2    However，for the same reason，music can be very beneficial if one is in pain．By distracting （分心） the mind from the pain，music，people say，can lower stress and anxiety levels．This，of course，can lead to less pain．

Many people enjoy relaxing music in the evening prior to going to bed．    3    While the validity of the idea is still being assessed，the lowered stress can even be tied back to blood pressure．Similarly, according to researchers，listening to just 30 minutes of soft music every day may help with healthy blood sugar levels， through the lowering of stress and anxiety．

When it comes to heart health，there is speculation （推测） that it's not the style of music， but rather the tempo that makes it so good for your heart health．In one European study，participants listened to music as the researchers monitored their heart rates and blood pressure．    4     On the other hand，when the music slowed，the participants' stress and anxiety levels became lower and the effects on heart rates appeared to follow suit．

    5    But there is a whole range of other health issues that turning up the radio could be beneficial for，which is what makes music so valuable．

4 . I remember the day during our first week of class when we were informed about our semester（学期） project of volunteering at a non-profit organization．When the teacher introduced us to the different organizations that needed our help，my last choice was Operation Iraqi Children （OIC）．My first impression of the organization was that it was not going to make enough of a difference with the plans I had in mind．

Then，an OIC representative gave us some details，which somewhat interested me．After doing some research， I believed that we could really do something for those kids．When I went online to the OIC website，I saw pictures of the Iraqi children．Their faces were so powerful in sending a message of their despair（绝望） and need that I joined this project without hesitation．We decided to collect as many school supplies as possible，and make them into kits——one kit，one child．

The most rewarding day for our group was project day，when all the efforts we put into collecting the items finally came together．When I saw the various supplies we had collected，it hit me that every kit we were to build that day would eventually be in the hands of an Iraqi child．Over the past four months，I had never imagined how I would feel once our project was completed．While making the kits，I realized that I had lost sight of the true meaning behind it．I had only focused on the fact that it was another school project and one I wanted to get a good grade on．When the kits were completed，and ready to be sent overseas，the warm feeling I had was one I would never forget．

In the beginning，I dared myself to make a difference in the life of another person．Now that our project is over，I realize that I have affected not only one life，but ten．With our efforts，ten young boys and girls will now be able to further their education．

There     1    (be) a dramatic rise in the number of extreme weather events over the past 20 years,    2    (cause) largely by rising global temperatures,according to a new report from the United Nations. From 2000 to 2019, there were 7,348 major natural disasters around the world,    3    (result) in USD 2,970 billion in economic loss．Much of this increase can be due to climate change. The findings show a critical need     4     (invest) in disaster prevention.

9 . Get up at 6 am, arrive at the hospital one hour earlier to help patients check in, and accompany patients during consultations… In recent years, “patient escorts” has emerged as a new industry, and those who have taken on this career are known as “people who sell time”, 26-year-old Zhang Tian is one of them.

September 4 was a lucky day for Zhang Tian. On this day, Zhang Tian saw a video about patient escorts on a short video platform. The daily routine of patient escorts shown in the video fascinated her and gradually inspired her to take this on as a business. She browsed through many platforms and read multiple information and found there indeed exists a certain demand for patient escorts, especially for the elderly, children, and pregnant women. Since she had never engaged in this kind of work before, she spent two days in major hospitals in Wuhan, in order to familiarize herself with all the departments on different floors, as well as the processes of medical consultation and preparation for surgery.

After preliminary preparatory (预备的) work, Zhang Tian posted a video of myself-introduction on major social platforms, talking about the help and services a patient escort provides, as well as some tips for a quick and convenient medical consultation. At first, she was a little worried that her video would go unnoticed. However, after she uploaded the video, it got over 100 likes and she received her first ever offer as a patient escort.

The memory of her first task is still alive and fresh in her mind. She received a phone call on September 9 from a man whose father was seriously ill and might need surgery. He wanted Zhang Tian to accompany his father through his consultation and treatment.” Zhang Tian made full preparations before meeting her first client and did a very good job despite her nervousness.

“Later, the family expressed their gratitude to me over and over again, which warmed my heart and gave me a sense of achievement.” Zhang Tian said.

Why do we dream？Scientists aren't completely sure,and they have diverse    1     (idea)．Dreams might be a side effect of memory making.When you sleep,your brain sorts through everything     2     happened during the day，trying to link new experiences to old memories.As it     3     (connect) things，your brain turns them into a story,and you get a dream．