水准面是处处与铅垂线相切的连续封闭曲面。

单项选择题等高线应与山脊线及山谷线平行。

单项选择题“My boyfriend of nearly two years had dumped me for an airheaded cheerleader.” In this sentence, the word dumped means __________.A. put something somewhere in a careless untidy wayB. got rid of something that you do not wantC. ended a relationship with someoneD. told someone all your problems and worries