【简答题】O是面 上一定点, 是面 上 的三个顶点, 分别是边 对应的角.以下命题正确的序号是 . ①动点P满足 ,则 的外心一定在满足条件的P点集合中. ②动点P满足 ,则 的内心一定在满足条件的P点集合中. ③动点P满足 ,则 的重心一定在满足条件的P点集合中. ④动点P满足 ,则 的垂心一定在满足条件的P点集合中.
【判断题】Richardson is often regarded as the founder of the domestic English novel.
【简答题】Richardson is often regarded as the founder of the ______ English novel since his novels focus on the limited problems of marriage and other family problems.
【多选题】水准基点是沉降观测的基准,因此水准基点的布设应满足的要求有(