郑和下西洋不能持续的根源是 （ ） A．不计经济效益 B．明
“以前，感觉国家很抽象、离我很遥远；但现在，感觉国家很具体、很真实”，这是四川灾区百姓发自内心的感言。在重大灾难里，国家“不抛弃、不
根据父系血缘关系的亲疏确定政治等级、巩固国家统治的制度是 A.禅让制 B.分封制 C.宗法制
在T ℃时，某NaOH稀溶液中c(H＋)＝10－a mol·L－1，c(OH－)＝10－b mol·L－1，已知a＋b＝12。向该溶液中逐滴加入pH＝c的盐酸(T ℃)，测得混合溶液的部分pH如下
Where did you find the professor who made the speech yesterday？” “It was in the hall ______ the students often have a meeting.” A. where
互联网已经不再是传统意义上的信息网络，它更是一个物质、能量和信息互相交融的物联网，互联网对传统制造业带来的颠覆在发达国家也已经出现。
Jane was disappointed that most of the guests_______when she _____at the party. A. left; had arrived B. left; arrived C. had left; had arrived D. had left; arrived
