Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.

Under the city streets

While skyscraper offices and elegant apartment blocks remain the public face of most major cities, these cities also have a mass of secret tunnels and .......(27)...... pipes below ground which keep everything working. This other world exists, forgotten or neglected by all but a tiny number of engineers and historians.

 For example, there are more than 150 kilometers of rivers under the streets of London. Most have been covered over and, sadly, all that .......(28)...... is their names. Perhaps the greatest loss to the city is the River Fleet, a once great river which previously had beautiful houses on its banks. It now goes underground in the north of the city and flows into the River Thames by Blackfriars Bridge.

 The London Underground has 1,000 kilometers of underground railway tracks winding under the capital and more than 100 stations .......(29)...... street level. Along some underground railway lines, commuters can sometimes catch a brief glimpse of the platforms of more than 40 closed stations which have been left under the city. .......(30)...... some are used as film sets, most lie forgotten. Some have had their entrances on the street turned into restaurants and shops, but most entrances have been .....(31)...... down.

Mark the letter A, B, C, or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions.

 Every (A) students (B) was sick last week, (C) so the professor (D) canceled the lecture.

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.

 Basic to any understanding of Canada in the 20 years after the Second World War is the country's impressive population growth. For every three Canadians in 1945, there were over five in 1966. In September 1966 Canada's population passed the 20 million mark. Most of these surging growth came from natural increase. The depression of the 1930s and the war had held back marriages, and the catching-up process began after 1945. The baby boom continued through the decade of the 1950s, producing a been exceeded only once before in Canada's history, in the decade before 1911, when the prairies were population increase of nearly fifteen percent in the five years from 1951 to 1956. This rate of increase had been settled. Undoubtedly, the good economic conditions of the 1950s supported a growth in the population, but the expansion also derived from a trend toward earlier marriages and an increase in the average size of families. In 1957 the Canadian birth rate stood at 28 per thousand, one of the highest in the world.

 After the peak year of 1957, the birth rate in Canada began to decline. It continued falling until 1966 it stood at the lowest level in 25 years. Partly this decline reflected the low level of births during the depression and the war, but it was also caused by changes in Canadian society. Young people were staying at school longer; more women were working; young married couples were buying automobiles or houses before starting families; rising living standards were cutting down the size of families.

 It appeared that Canada was once more falling in step with the trend toward smaller families that had occurred all through the Western world since the time of the Industrial Revolution. Although the growth in Canada's population had slowed down by 1966 (the increase in the first half of the 1960s was only nine percent), another large population wave was coming over the horizon. It would be composed of the children of the children who were born during the period of the high birth rate prior to 1957.

 What does the passage mainly discuss?