赞题库-背景图
单项选择题

Today, California"s public schools are a disaster. 1 by dysfunction and disrepair, they rank at the bottom of the country, just as the U.S. now sits at the bottom of the industrialized world by most 2 of educational achievement. The World Economic Forum 3 the U.S."s educational system 26th in the world, 4 behind those countries like Germany, Finland, 5 , Demark, Canada and Singapore. In science and math, the U.S. 6 even worse.
We"ve been talking about America"s education decline for three 7 now, so much 8 we are numbered by the discussion. But the 9 of that crisis are only just becoming fully 10 . As American education 11 , the median wages of the American worker have 12 , and social mobility—the beating heart of American dream—has slowed to a standstill. Education is and always has been the fastest way 13 the socioeconomic ladder. And the 14 from a good education remains evident even in this weak recovery. If you 15 high school, you will have a depressed standard of living for the rest of your life.
The need for better education for most Americans has 16 been more urgent. While they have been sleeping, the rest of the world 17 its skills. Countries in Europe and Asia have worked hard to increase their college-graduation 18 , while the U.S."s has flatlined. Other countries have focused on math and science, 19 in America degrees have 20 in "fields" like sports exercise and leisure studies.

A.though
B.since
C.while
D.however