材料一：余相信美国之政策意在支持自由之民族以抵抗少数武装分子或外来压力之征服企图。

──杜鲁门致国会咨文

材料二：美国应该尽力协助世界回复至经济健全的常态……美国政府能够尽力缓和局势，协助欧洲走上复兴道路。

──马歇尔在哈佛大学的演说

材料三：本公约各缔约国……决定联合一切力量，进行集体防御。

──《北大西洋公约》

请回答：

《海国图志》的作者是林则徐，他提出了“师夷长技以制夷”的主张。

Are you good ____children?

(C)

    Hello, boys and girls! My name is Dick. I'm a boy. I'm a robot (机器人). Please look here. These are my hands. My arms are long. I have no hair. This is my face. I have two big eyes, a long nose and a wide mouth. Here are my big ears. ⑶I have short legs and two big 　　 (foot). I can walk(步行). I can speak Chinese, but I can't speak English. I'm your good friend.