A:—Who is she?—She's Tomy.
B:—Who is he?—He's Jim.
cos150°的值为( )
一个多边形的内角和等于外角和的3倍,则多边形的边数是____
《咏雪(世说新语)》文末为什么要强调谢道韫是王凝之的妻子?