Question: Read this and answer the question

Sport plays an important role in Estonian culture. After declaring independence from Russia in 1918, Estonia first competed as a nation at the 1920 Summer Olympics, although the National Olympic Committee was established in 1923. Estonian athletes took part of the Olympic Games until the country was annexed by the Soviet Union in 1940. The 1980 Summer Olympics Sailing regatta was held in the capital city Tallinn. After regaining independence in 1991, Estonia has participated in all Olympics. Estonia has won most of its medals in athletics, weightlifting, wrestling and cross-country skiing. Estonia has had very good success at the Olympic games given the country's small population. Estonia's best results were being ranked 13th in the medal table at the 1936 Summer Olympics, and 12th at the 2006 Winter Olympics.

What city hosted the 1980 Summer Olympics Sailing regatta?
Answer: Tallinn
Question: Read this and answer the question

The net quality of a ground reflection depends on the topography of the surface. When the irregularities of the surface are much smaller than the wavelength, we are in the regime of specular reflection, and the receiver sees both the real antenna and an image of the antenna under the ground due to reflection. But if the ground has irregularities not small compared to the wavelength, reflections will not be coherent but shifted by random phases. With shorter wavelengths (higher frequencies), this is generally the case.

What is the net quality of the ground dependent of?
Answer: topography
Question: Read this and answer the question

The redevelopment of the city was planned by Sir Patrick Abercrombie in his 1943 Plan for Plymouth whilst simultaneously working on the reconstruction plan for London. Between 1951 and 1957 over 1000 homes were completed every year mostly using innovative prefabricated systems of just three main types; by 1964 over 20,000 new homes had been built transforming the dense overcrowded and unsanitary slums of the pre-war city into a low density, dispersed suburbia. Most of the city centre shops had been destroyed and those that remained were cleared to enable a zoned reconstruction according to his plan. In 1962 the modernist high rise of the Civic Centre was constructed, an architecturally significant example of mid twentieth century civic slab-and-tower set piece allowed to fall into disrepair by its owner Plymouth City Council but recently grade II listed by English Heritage to prevent its demolition.

In the postwar period to 1964, how many houses were built in Plymouth?
Answer:
over 20,000