下列有关战争的说法中正确的有（　　） 

①希波战争导致希腊走向衰落 

②经过长期扩张，2世纪，罗马帝国地跨欧、亚、非三大洲，地中海成为其内海 

③第一次世界大战从1861年到1865年，历时4年多，造成重大的物资破坏和人员伤亡 

④1944年6月，美英盟军发起诺曼底登陆战役，开辟了欧洲第二战场。

根据短文理解从A、B、C、D四个选项中选择最佳答案填空。

    Once a rich woman invited Martin Brown, a famous singer to sing for her friends. But she 1 him to have dinner with them. She told him to eat 2 the servants(仆人).

    After the meal Martin stood up and said to the servants, “Now, my good friends, I 3 for you.” He sang several songs and the servants 4 quite pleased.

    Then the rich woman asked 5 to come to the sitting-room. “We are waiting for your songs. 6 you ready?” the woman asked.

   “I am 7,” Martin said. “I have sung already(已经). I usually sing 8 in one evening, and I can't sing 9.”

    And with a polite(礼貌) “10”, he left the rich woman's house.

如图，抛物线 $y=\frac{1}{2}{x}^2+bx+c$ 与直线 $y=\frac{1}{2}x+1$ 交于A、B两点，点A在x轴上，点B的横坐标是2．点P在直线AB上方的抛物线上，过点P分别作PC∥y轴、PD∥x轴，与直线AB交于点C、D，以PC、PD为边作矩形PCQD，设点Q的坐标为（m，n）．

利用图象分析问题是物理学中常用的方法，其中的斜率、面积通常具有明确的物理意义．