阅读下列材料，并回答问题。

材料一：   卫鞅曰：“治世不一道，便国不法古。故汤武不循古而王，夏殷不易而亡……”

材料二：   从商鞅变法到秦始皇即位前的一百多年间，秦军同六国共交战65次。

材料三：   魏主欲变北俗，引见群臣。帝曰：“今欲断诸北语，一从正音（禁用鲜卑语，统一使用汉语）。……三十已下，见在朝廷之人，语音不听仍旧，若有故为，当加降黜。” ——《资治通鉴》

“它是中华人民共和国外交发展的一个阶段性界碑，它是从革命运动外交向国家外交过渡的一次关键性转变，标志着新中国外交方针的最终形成。”这里的“它”是指（    ）

    Today is Saturday. It's seven o' clock in the evening now. Jack's family are busy.

    Jack is in his room. There are some clothes on his bed. He is looking for his blue T-shirt. At eight, he will (将) have dinner with his friends at a restaurant. Jack's sister, Ann, is watching TV. Volleyball (排球) is her favourite sport and she often plays it with her friends at weekends. Volleyball tickets are expensive so she often watches volleyball matches on TV.

    Where are Jack's parents? Oh, his father is searching for some information about Hainan on the Internet. He will drive to Hainan with his manager tomorrow. Jack's mother is doing some washing. Oh, where are Jack's grandparents? They are in the park. Jack's grandfather is walking with the dog. Jack's grandmother is dancing (跳舞) there.