28. The word "concept" in line 16 is closest in meaning to

　　(a) location

　　(b) type

　　(c) complexity

　　(d) thought

　　29. The word "virtually" in line 21 is closest in meaning to

　　(a) effectively

　　(b) occasionally

　　(c) thoroughly

　　(d) undeservedly

　　30. Which of the following is NOT true about immigrants

　　(a) they were subjected to an official quota in the Immigration Act from 1924

　　(b) during the 1900s immigrants numbered 1 percent of the total population

　　(c) settlers of Hispanic origin arrived centuries before those from Europe

　　(d) numbers began to be limited from 1921

　　31. Which of the following can be inferred from the passage

　　(a) preserving a developing "American" culture was a major factor leading to the introduction of the quota system

　　(b) racial and ethnic assimilation did not occur as planned

　　(c) racial and ethnic tensions would have increased if the quota system had not been introduced

　　(d) the quota system was introduced to ;limit population growth