By far, the most technologically challenging railway ever built was probably the Qinghai-Tibet Railway,     1     (complete) in 2006, connecting Xining to Lhasa. The railway was first planned in the 1950s, but the technical difficulties were too much     2     (overcome). It was not until 1984     3     the first 814-kilometer section of the railway, from Xining to Golmud, was completed.

The biggest issue was the permafrost — frozen earth. In the summer, in many places the top layer of the permafrost melts and     4     (turn) to mud, making the ground unstable. A     5     (various) of solutions were used to get around this. In some cases, railway bridges     6     (build). In other cases, pipes were installed under the ground to keep it frozen during the summer. Finally, in some areas it was     7     (possible) to build the railway over the permafrost, so engineers tunneled through it.

It is hoped that the experience of building the Qinghai-Tibet Railway can be used in     8     new project, linking Kashi, China with Islamabad, Pakistan along the Karakoram Highway, the highest highway in the world. This railway will travel 1,000 kilometers through the Pamir Mountains,     9     are nicknamed the Roof of the World. Building such a railway will be     10     (undoubted) a technical challenge. It has not yet been announced when construction on this project will start.

Many people often get     1     (stick) in traffic jams when they go to work. How tired and angry they often feel! But the problem is that     2     number of cars is still increasing. And traffic is one of the major     3     (cause) of global warming and climate change. What's more, some types of cancer are related     4     traffic pollution. We all know that cars are bad for us. But we are still addicted     5     cars. Some advice has been given to help people give up cars. For example, we should use public transport or share cars. As we know, up to ninety people can travel in one bus     6     the same number will need at least eighteen cars. Do your shopping in the shops that are just around the corner instead of     7     (drive) to the other side of the town. Sharing cars is much     8     (cheap) and it is kinder to the environment. Let's     9     (take) action to solve the problem and do     10     (which) of the things that suit us.

Thousands of years ago, the West Lake in Hangzhou was connected to the sea. The Qiantang River, not far away from the West Lake,     1    (enter) the sea in the eastern part of this area. The solid material such as sand, stones and mud carried by the river     2    (eventual) settled at the bottom and blocked the connection between the West Lake and the sea,     3     (make) it an inland water.

Since the ninth century AD, the breathtaking scenery of the West Lake in all seasons     4    (appear) time and again in poems, stories and legends.     5     impresses people most is that there are about 630 legends of the West Lake alone. Su Dongpo wrote a poem to praise the West Lake     6     compared it to Xizi, a Chinese legendary     7    (beautiful). From then on, the West Lake got another elegant name — Xizi Lake.

In 2011, West Lake Cultural Landscape of Hangzhou was included     8     the World Heritage List. It is now visited by an endless stream of     9    (visitor) from home and abroad. Perhaps some of them will add     10    (they) own stories to West Lake’s wealth of literature.