下列四组生物中，能够生活在同一生态系统中的是（　　）

关于弹簧的劲度系数K，下列说法正确的是（   ）

阅读下面古诗。
                                                                                                  陇西行 陈陶
                                                                                              誓扫匈奴不顾身，

                                                                                              五千貂锦丧胡尘。

                                                                                              可怜无定河边骨，

                                                                                              犹是春闺梦里人。