Poor environment is connected with poor health. Now a new public-health     1     (tend)is becoming apparent: Making indoor air cleaner.

Let’s take schools for example. Across Denmark, France, and Sweden, researchers found that indoor-air quality in 66% of classrooms fell short     2     healthy standards. Outdoor-air pollution can get inside buildings — childhood     3     (expose)can affect their physical development and academic performance, and cause cancer.

The problem extends well beyond classrooms. Many people spend more than 90% of their time     4     (stay)indoors. Spaces in buildings with poor air may cause a range of diseases — headaches, shortness of breath, coughs and discomfort of eye, nose, throat and skin. Poor air     5     (blame)for decreased productivity in the past few years.

Covid-19 has brought a new urgency to the matter     6     (great). More investment would be well spent. Better indoor air improves academic development — math     7     reading scores go up. Meanwhile pupils are     8     (attentive)in class. Poor air indoors is the     9     (forget)part when people improved public health. Covid-19 should lead policymakers to focus on the problem,     10     is of great importance for people’s well-being.

Many scientists say we are now entering the Earth’s sixth mass extinction.If a sixth mass extinction    1    (occur ),scientists who have studied the issue believe that up to three quarters of all species on Earth could die out Of course, as we humans depend on so many species for our survival, we would also be at risk of    2    ( die) out. Our world and our lives depend on the balance in nature between animals and plants. Without forests, we would have no air to    3    ( breath ),and without clean water we would be unable to survive.

It is reported that at present a city in Japan has a problem with graffiti(涂鸦). However, it is not the usual type of graffiti with paint from spray cans     1    (use) to write on walls. It is graffiti in sand.

Officials in the city of Tottori are asking tourists to give up     2     (write) messages and drawing pictures in the sand of its giant sand dunes (沙丘). The officials say the graffiti causes damage to the dunes,     3     destroys the pleasure others get in looking at the sand.

More than 3,300 cases of "sand graffiti"     4     (occur) at the tourist spot in the past decade. In January, two overseas tourists were ordered     5     (erase) a 25-meter-long message that read "Happy Birthday Natalie".

The Tottori Sand Dunes are famous throughout Japan     6     their natural beauty. They are the largest and longest sand dunes in the country and form part of     7     scenic coastal park on the sea of Japan coast. The biggest dune is 50 meters high.

The local government wants to improve tourists' understanding of the     8     (important) of the dunes. It will set up much     9     (many) signs in English, Chinese and Korean asking people to respect the dunes. A spokesman said, "We are concerned about whether the rules are     10     (complete) understood, and we want to continue to protect views of the beautiful sand dunes."