If you go out to the fields at night in spring or summer, you can hear frogs singing     1    (happy) here and there. It seems as if they were performing a field group singing.

The frog is a good and useful creature that benefits human beings. They can catch fast-moving     2     (insect). Each frog eats a large number of pests (害虫) that are     3     (harm) to crops. This little creature is regarded as “the natural enemy of pests”.

But now frogs     4     (get) fewer and fewer. This is     5     they are killed and put on the table as a delicious dish by their chief enemy, human beings. It is a shameless and cruel act, isn’t it?

The cause that is responsible     6     the rapid reduction of frogs is that farmers use insect killers to kill pests and frogs get killed as a result of drinking poisoned water while     7     (eat) poison-killed insects.

Something must be done as soon as possible     8     (save) frogs. If we don’t punish those     9     sell and kill frogs to make money, then one day all of us     10     (punish) by nature for failing to keep them.

High on the Qinghai-Tibet Plateau     1    (lie) China’s “water tower” Sanjiangyuan. It is home to the headwaters of China’s three rivers: the Yellow River, Yangtze River, and Lancang(Mekong) River. It is the three rivers     2     provide water for about half the population of China. However, human activities are putting this ecosystem     3     risk. Hopefully, though, we can repair this damage. In 2016, the Chinese government established Sanjiangyuan National Park in Qinghai province. The park,     4    (schedule) to open in 2020, has increased the area’s green coverage and attracted more wildlife. The local government has also made great effort to improve biological diversity. The success of Sanjiangyuan will mark the start of a     5    (green) future. With Sanjangyuan     6    (take) the lead, nine other regions in China     7    (choose) by a field conservation station to carry out projects over the past three years,     8     will form a national park system together. The idea of a national park system is still new in China, but    9    (it) realization is urgent. After all, building an ecological civilization bears great       10    (important) in the development and progress of human civilization.