题目

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=μ       B．tanα=μ    C．cosα=μ  D．sinα=μ                答案：B解析:略 By the end of this year, 160 new students ___ in the English Department of this world famous university．A.have enrollB.will have enrolledC.have been enrolledD.will have been enrolled