简述世界各国对社会保险基金投资方式的一般规定。
参考答案：
My sister ________ a book about France last year but I don't know whether she has finished it. [ ]
A. has written
B. wrote
C. had written
D. was writing
生产关系是最活跃、最革命的因素，是社会发展的最终决定力量。 ( )
