总体方差未知时，以下可以作为总体方差估计值的是（）。
未知类型：{'options': ['S', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_28f2474a-8d8c-412f-95c0-7df65dd99d6c.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_263213bc-0240-4bc1-853a-96c1e5cd1753.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_bfed0ae1-ba7c-4210-98e1-e187dc80033c.png"]'], 'type': 102}
未知类型：{'options': ['S', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_28f2474a-8d8c-412f-95c0-7df65dd99d6c.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_263213bc-0240-4bc1-853a-96c1e5cd1753.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_bfed0ae1-ba7c-4210-98e1-e187dc80033c.png"]'], 'type': 102}
举一反三
- [img src="http://edu-image.nosdn.127.net/E9ECD91FC8FB3437CBAE9E731E05C1F9.bmp?imageView&type=jpeg&thumbnail=890x0&quality=100"] 未知类型：{'options': ['[img src="http://edu-image.nosdn.127.net/844D4F13280FCB22936CC001C2655964.bmp?imageView&type=jpeg&thumbnail=890x0&quality=100"]', '0', '1', '[img src="http://edu-image.nosdn.127.net/39355C3F2BE9AE15346505596CAABAF4.bmp?imageView&type=jpeg&thumbnail=890x0&quality=100"]'], 'type': 102}
- 下列矩阵，哪一个是正交矩阵（ ） 未知类型：{'options': ['[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_e3bcbe32-bf4f-4dd7-87eb-435166d4a694.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_2dd5a805-5f17-4578-950f-b0e99cb4ace5.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_fb404ce8-29fb-4a21-9f66-2e1cc1e8e6b2.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_6238ef9e-3ec5-4c01-8429-4fbbb82bc5ff.png"]'], 'type': 102}
- 设[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_067016aa-77f2-4aff-bd36-e3fa5f1bd893.png"],[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_358ab06c-7f19-4ae6-ba82-424c72bd4d18.png"],则[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_2b561af0-b65d-4e5e-936b-72b15b4f0f56.png"][img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_92284d1b-6fe3-4dc1-a732-618796cd01a4.png"] A: 6 B: 10 C: 8 D: 4
- 以下对相关系数与回归系数的描述正确的是 未知类型：{'options': ['[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_a239429a-7fee-4b87-8988-34ecbff62f78.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_8e840276-5eb5-496e-99e5-dbf0fc08a23b.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_44c8e13f-08e0-425a-b275-0409b8954e16.png"]', '[img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_b013f5a5-447f-46ad-89ec-f4a2c5927468.png"]'], 'type': 102}
- [img src="http://edu-image.nosdn.127.net/C8EC0B0C890042F81AB9CF0941243122.bmp?imageView&type=jpeg&thumbnail=890x0&quality=100"] 未知类型：{'options': ['2', '0', '1', '[img src="http://edu-image.nosdn.127.net/EAB437E744FF87F763873F106CCCE3E9.bmp?imageView&type=jpeg&thumbnail=890x0&quality=100"]'], 'type': 102}