未知题型 根据《城市居住区规划设计规范》的规定，住宅侧面间距、条式住宅、多层之间不宜小于( )m，高层与各种层数住宅之间不宜小于13m。

单项选择题 二阶线性齐次微分方程y"-y=0的通解是( ) A．C1—C2ex B．C1ex十C2xe[x C．C1+C2ex D．C1e-x+C2xe-x

未知题型 阅读短文，完成填空：Antarctica is the continent which is the most southern area of land on the Earth and is mostly covered with ice. This is one of the driest and 21 in the world． But people from all over the world come to 22 there. Near the South Pole， three thousand people live together in a place 23 Amundsen-Scott Station.The station has libraries， cinemas， shops， sports rooms， canteens and laboratories. There is electricity， and they have 24 ——the system that they use to have a conversation with someone in another place. And they have 25 ——electronic machines that store information and use programs to help them find， organize， or change the information. But the people here 26 travel by car， or train， or bus， because there aren't any roads or railways near the station. They travel by ship， helicopter， planes， or snow tractors， or 27 dogs.There aren't 28 trees or flowers there， but there are hundreds of different birds and other animals. Most of the people here are 29 . They study plant and animal life and how ice moves. The ice can tell us about changes in climate. Ray Kingman is an expert at Amundsen-Scott station telling us on the phone， 'This is my second year here. It's very interesting and beautiful place， but life is very hard 30 . In the summer we can go swimming in hot pools of water. We welcome newcomers here for further study of the continent ! '材料题请点击右侧查看材料问题 查看材料 A.warm areasB.coldest placesC.cool areasD.hottest places