如图所示,汽车在倾斜的弯道上拐弯,弯道的倾角为θ,半径为r,则汽车完全不靠摩擦力转弯的速率是____.
当今世界上土地资源遭受破坏最主要原因( )
设a=log123,b=(13)0.2,c=213,则( )
—Sir, could I hand in my homework a bit late?
— __________, since you've been unwell these days.