PM stands for particulate (微粒的) matter: the term for a mixture of solid particles (粒子) and liquid droplets in the air. Some particles are large or dark enough to be seen by our eyes. Others are so small that they can only     1     (discovery) with a microscope.

These particles come in many sizes and     2     (shape) and can be made up of many different chemicals. Some come directly from a source, such as fields or fires. Most particles form in the atmosphere as a result of complex reactions of chemicals,     3    are pollutants from power plants, industries and automobiles.

Particulate matter     4     (contain) microscopic particles that are so small that they can be breathed in and make one seriously ill. Some particles less than 10 micrometers in diameter can get deep into your lungs     5     some may even get into your bloodstream. Of these, particles less than 2.5 micrometers in diameter, also known as PM2.5, create the     6     (great) risk to health.

    7     (fortune), every day the Air Quality Index(AQD) tells you how clean or     8     (pollute) your outdoor air is, along with associated health effects that may be     9    concern. The AQI translates air quality data into numbers and colors that help you understand when     10     (take) action to protect your health.

Martin Strel swims with a knife     1       (fasten) to his right leg—in case he meets sharks and other     2       (dead) sea life in the world’s wildest waters.     3       61-year-old marathon swimmer has announced the       4       (tough) challenge of his life: a 10,000-mile-around-the-world journey on water       5       (draw) public attention to the increasing water       6     (pollute). He aims to circle the globe in about 450 days, passing through oceans, rivers,    7       (canal) and other bodies of water in more than 100 countries. He will swim about 5 to 12 hours each day, depending on the weather. A boat will go     8     him and offer emergency support and space for small breaks.

Since 2000, Strel     9     (swim) the entire length of five rivers in China, America, etc. Strel will not be alone in the water. He says he welcomes     10     is interested in joining him for parts of the route.

Life pressure can be big enough, so we need to be surrounded by warm words. A phenomenon    1    (know)as “in-need-of-praise” has taken Chinese social media by storm and a new trend-seeking praise from     2     (stranger)—has gone popular on social media among China’s young people. Recently, many chat groups     3     (form) to show kindness and support to members. These“in-need-of-praise” chat groups are a reflection of Chinese culture where     4     (open) seeking and giving praise is uncommon,     5     (lead)many people to hide their true emotions.

For young people, gaining     6     (recognize) from peers is more important than getting approval from older generations. They can feel     7     sense of belonging and gain encouragement,     8     is beneficial to their mental health.

Most of us like praise, because it can raise our spirits, warm our hearts and decrease fears and self-doubt. However, anyone giving or receiving praise in such groups should be     9     (care). Such praise comes at a cost. And the biggest risk is the constant emphasis on the “false self”, which makes     10     harder to see the “true self”.

Many parents don’t know how much exercise their children need to do every day to stay     1     (health). The National Health Service guidance states that children     2     are aged from five to eighteen should do one hour of exercise every day, which about seventy percent of adults in the UK never mind. The research of 2,000 adults     3     (find) that only a quarter knew the exercise time recommended for young people.

The Youth Sport Trust leader, Ali Oliver said, “We have seen a drop in young people’s physical activity in recent     4     (year).” It is often     5     (report) that pupils are taken out of PE lessons to prepare for exams.

Meanwhile, figures from Sport England show only 17.5% of children are doing sports continuously. There is also a     6     (differ) among children from various economic (经济) backgrounds, with 39% of those from poor families doing     7     (little) than thirty minutes of exercise a day, compared with 26% from rich families.

This week thousands of people will get together     8     (celebrate) National School Sport Week, with     9    aim of promoting (推进) the importance of exercise and bringing great benefit     10     young people.

Many schools started online courses for students to study. at home on account of the spread of COVID-19.    1    , the outcome turned out to be not satisfying, because the online education required teachers to carry out live stream courses using mobile phone software and properly interact with students, which proved    2    challenge for many teachers.

Some teachers discovered they left the microphones off before finishing the online courses, and others were frequently interrupted by    3    (they) young children's shouting or crying. Sometimes they had to repeatedly reconnect to the platform due    4    poor Internet connection,    5    annoyed both the students and the teachers. Some schools offered online courses for each subject including sports. Teachers found it awkward    6    (give) instructions online because many children did not have enough space to move. Some parents complained that they had to join several different chat groups of different    7    (subject) . They also hated to accompany their children taking online courses just to make sure their children were    8    (full) concentrated instead of    9    (play) video games.

Schools should not put any unnecessary academic burden on primary and secondary students through online classes, the Ministry of Education said on Wednesday. It was recommended that online courses    10    (link) to infection prevention and psychological health guidance.