11. The asphalt at La Brea seeps to the surface, especially in the summer, and forms shallow puddles that would often have been concealed by leaves and dust.

　　The word "concealed" is closest in meaning to which of following?

　　(A) highlighted

　　(B) covered

　　(C) transformed

　　(D) contaminated

　　12. The ocean bottom --- a region nearly 2. 5 times greater than the total land area of the Earth --- is a vast frontier that even today is largely unexplored and uncharted, until about a century ago, the deep-ocean floor was completely inaccessible, hidden beneath waters averaging over 3,600 meters deep.

　　The word "inaccessible" is closest in meaning to which of following?

　　(A) unrecognizable

　　(B) unreachable

　　(C) unusable

　　(D) unsafe

　　13. The DSDP's drill ship, the Glomar Challenger, was able to maintain a steady position on the ocean's surface and drill in very deep waters, extracting samples of sediments and rock from the ocean floor.

　　The word "extracting" is closest in meaning to which of following?

　　(A) breaking

　　(B) locating

　　(C) removing

　　(D) analyzing

　　14. Today, largely on the strength of evidence gathered during the Glomar Challenger's voyages, nearly all earth scientists agree on the theories of plate tectonics and continental drift that explain many of the geological processes that shape the Earth.

　　The word "strength" is closest in meaning to which of following?

　　(A) basis

　　(B) purpose

　　(C) discovery

　　(D) endurance

　　15. 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 this surging growth came from natural increase.

　　The word "surging" is closest in meaning to which of following?

　　(A) new

　　(B) extra

　　(C) accelerating

　　(D) surprising

　　16. When the prairies were being settled, undoubtedly, the good economic conditions of the 1950's 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.

　　The word "trend" is closest in meaning to which of following?

　　(A) tendency

　　(B) aim

　　(C) growth

　　(D) directive

　　17. After the peak year of 1957, the birth rate in Canada began to decline. It continued falling until in 1966, it stood at the lowest level in 25 years.

　　The word "peak" is closest in meaning to which of following?

　　(A) pointed

　　(B) dismal

　　(C) mountain

　　(D) maximum

　　18. Although the growth in Canada's population had slowed down by 1966 (the increase the first half of the 1960's was only nine percent) , another large population wave was coming over the horizon. It would be composed of the children who were born during the period of the high birth rate prior to 1957.

　　The phrase "prior to" is closest in meaning to which of following?

　　(A) behind

　　(B) since

　　(C) during

　　(D) preceding

　　19. Advocates of organic foods --- a term whose meaning varies greatly --- frequently proclaim that such products are safer and more nutritious than others.

　　The word "Advocates" is closest in meaning to which of following?

　　(A) Proponents

　　(B) Merchants

　　(C) Inspectors

　　(D) Consumers

　　20. There are numerous unsubstantiated reports that natural vitamins are superior to synthetic ones, that fertilized eggs are nutritionally superior to unfertilized eggs, that untreated grains are better than fumigated grains, and the like.

　　The word "unsubstantiated" is closest in meaning to which of following?

　　(A) unbelievable

　　(B) uncontested

　　(C) unpopular

　　(D) unverified