题型:问答题 简答题 Take time lo relax by listening to music, reading a book or just spending some time alone.Relaxing allows you _______ to your students with more energy. [ ]A. return B. to returnC. returning 查看答案
题型:问答题 简答题 如图所示,修建铁路、公路的路堤和路堑时,允许的边坡倾角最大值叫做“自然休止角”,如果边坡倾角超过自然休止角α会导致路基不稳定,关于自然休止角α与土壤颗粒之间的动摩擦因数μ的关系式正确的是( )A.cotα=μB.tanα=μC.cosα=μD.sinα=μ 查看答案