题目

51. My father has made a full__________(recover) from the operation. 52. Mrs. Wu told us that the moon ______ (go) around the earth. 53. I happened to be upstairs at dusk _________ the window was open. 54. It’s no pleasure __________(look) through these any longer because nature is one thing that rally must be experienced. 55. The situation is easy ___________(change) if you take my advice. 56. In some ways they are very different ___________ one another. 57. __________(actual) all languages change and develop when cultures meet and communicate with each other. 58. This is because设F1、F2分别是椭圆C:+=1(a＞b＞0)的左、右焦点,l为左准线,A1、A2分别为其长轴的左、右端点.(1)若椭圆上的点M(1,)到F1、F2的距离之和为4,求椭圆方程;(2)有一个猜想:“设P(x1,y1)、Q(x2,y2)(y1y2≠0)是椭圆C上的任意两点，若P、F1、Q三点共线,则直线PA1、QA2、l共点.”你认为这个猜想能成立吗？请说明理由.