Directions : There are 20 blanks in the following passage . For each blank there are four choices A) , B) , C)and D)on the right side of the paper . You should choose the answer that best fits into the passage . Then mark the corresponding letter on the Answer Sheet with a single line through the centre. Japan , whose population is aging faster than that of any other nation , may provide a laboratory for the challenges that developed societies will increasingly face . Such challenges 1 rising pension( 养老金 ) and medical costs and greater stress 2 a shrinking number of family caretakers , 3 to a recent study published by the Population Reference Bureau , Inc in Washington D . C . the proportion of the Japanese population 4 65 and over is expected to 5 than double between 1985 and 2025 , 6 from 10 % of the total population to 23 %, 7 to decreasing birth and death rates . 8 Japan’s elderly have been Considered “honorable elders” who 9 a special place in the home , according to Linda G . Martin , author of 10 National Academy of Sciences Committee on Population . 11 the proportion of elderly living with their children 12 from 77 % in 1970 to 65 % in 1985 . Increased 13 of middle-aged women , the traditional caretakers 14 the elderly , means that a 15 proportion of elderly Japanese can 16 upon care by family members . The proportion of married 17 of childbearing age planning to depend on their 18 for support in old 19 decreased from 55 % in 1950 to 18 % in 1988 . 20 where such care is provided there is some evidence of considerable family stress and poor quality of care .