—How nice your schoolbag is!
—— .
A:Thank you very much
B:I don't think so
C:No,it isn't beautiful
D:please don't say so.
已知cosα=﹣45,α为第三象限角.
求sinα,tanα的值;
下列哪一项不是植物细胞工程的实际应用 ( )