The “natural” greenhouse effect refers to the fact that heat from the sun enters the atmosphere and warms Earth’s surface as short-wave radiation. Then the heat 【小题1】 (release) back into space. Greenhouse 【小题2】 (gas) in the atmosphere, such as methane and carbon dioxide, trap some of the heat, keeping Earth’s climate warm and habitable. Earth could not sustain life 【小题3】 this process.

Seeing the Northern Lights is an interesting experience for travelers. Whoever sees the lights wonders at this 【小题1】 (amaze) phenomenon. It can 【小题2】 (see) more easily in the countries that lie close to the Arctic Circle (北极圈). Sweden is on one of those countries where visitors can lose 【小题3】 (they) in these colorful ribbons in its sky. In Sweden, the Northern Lights usually appear in the winter months, but sometimes they appear【小题4】 (early) than usual.

Several regions become famous places for tourists 【小题5】 (observe) the Northern Lights, and Jukkasjarvi is one of them. This village is proud 【小题6】 its hotel made from ice. This ice hotel is known to organize guided tours 【小题7】 take its guests to Esrange Space Center. There visitors can dine at the camp in the wild while 【小题8】 (enjoy) the red, purple, green and blue lights shining above them. Besides, several private 【小题9】 (company) run dogsledding and snowmobile trips in the night to take tourists in the wild for 【小题10】 perfect view of these Northern Lights.

Surrounded by green woods and pools of water, the Chinese village Ding Wuling should be full of mosquitoes, especially during the summer time. 【小题1】, the tiny bloodsuckers(吸血动物) haven't been seen here in almost a century.

The village of Ding Wuling, 【小题2】   (locate) in the hills of China's Fujian province, 700 meters above sea level, is home 【小题3】   the hakka(客家)minority. But in recent years, the culture and architecture of this beautiful village have been beaten by 【小题4】 unbelievable affair-the absence of mosquitoes. Although it     【小题5】 (cover) by green trees in fact, the village has reportedly been mosquito-free for several 【小题6】 (decade).

It's unclear whether scientists ever carried out a research to get the real answer, but most of the people in Ding Wuling believe it has something to do with the frog-shaped stone outside the village. They believe that it is the “god frog” 【小题7】 keeps the mosquitoes at bay.

Another popular explanation is tied to the locals’ habit of collecting garbage and 【小题8】 (bury) it on the hillside near the village, which some believe helps keep Ding Wuling mosquito-free.

In 2016, when Chinese newspaper People's Daily 【小题9】   (origin) reported the story of this mosquito-free village, locals said they were hoping experts could soon provide a clear answer that had put Ding Wuling on the tourist map. Unfortunately, its mosquito-free story is still a mystery, so it's possible that the whole thing was made up 【小题10】 (attract) tourists.