Undoubtedly, Tibet is one of the 1. _________ places for human existence. It is cool in summer but freezing cold in winter. In Lhasa, the mildest city in Tibet, temperatures may 2. _________29 degrees Celsius in 3. _________ while plummeting to -16 degrees Celsius in winter! Sun radiation is extremely 4. _________in Tibet. The sunlight in Lhasa is so5. _________ that the city is called Sunlight City. The thin air can neither block off nor retain heat so that there are great temperature extremes on the same day! The 6. _________temperature in northern Tibet is subzero and winter arrives in October until the following May or June July and 7. _________ are the best time to visit the area, enjoying warm temperatures, intense sunshine, 8. _________ scenery and festive events May, June and September 9. _________the tourist season in east Tibet. In winter, roads are all blocked by heavy snow. Landslides and rock falls frequently10. _________, which will make travel difficult.