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.

    1     (save) Xizang antelopes from extinction, the Chinese government placed them under national protection.With the     2     (effect) measures, Xizang antelopes were removed from the endangered species list in 2015. People should also realize our planet needs variety to survive.     3     is important that all species—the good, the bad, and the ugly—should be treated equally.

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."

Chinese scientists have developed a kind of plastic that degrades in sea water and could help slow down the     1    (increase) serious plastic pollution in the ocean.

The new plastic can degrade in sea water over a period ranging from a few days to several hundred days,     2    (leave) small parts that cause no pollution, said Wang Gexia,     3     is a senior engineer. 

For a long time, people focused     4     white pollution on land. Plastic pollution in the sea only caught people’s attention when more and more     5    (report) about marine animals dying from it appeared in recent years.

Scientists combined water dissolution and biodegradation processes     6    (design) and invent     7     new plastic.

The research     8    (select) as one of the winning projects at a contest. The contest encouraged young Chinese scientists to develop groundbreaking technologies and was intended to inspire creativity. 

China has given top attention to     9    (environment) protection, contributing Chinese wisdom to     10    (resolve) global pollution problems.