题目

 It wasn’t _____the anti-Japanese war was over _______ his parents had died two years before    A. until; did he know                                B. until; that he knew                  C. unless; that he knew                              D. until; when he knew 答案：B8、命题A：两曲线F（x，y）=0和G（x，y）=0相交于点P（x0，y0），命题B：曲线F（x，y）+λG（x，y）=0（λ为常数）过点P（x0，y0），则A是B的充分不必要条件．