下列动物的胚胎发育方式不属于胎生的是（  ）

某人腰椎部因受外伤造成右侧下肢运动障碍，但有感觉。该病人受损伤的部分可能是在反射弧的：（     ）
①传入神经   ②传出神经    ③感受器    ④神经中枢   ⑤效应器

已知地球半径为R，同步卫星的半径为r．则同步卫星与在地球赤道上物体的向心加速度之比为____，同步卫星与近地卫星的线速度之比为____．

通读下面的短文，掌握其大意，然后从各题所给的A、B、C三个选项中选出一个最佳答案。

Dear Sally,

    How are you? I'm happy that you can do the things you 1 at home. I never have fun, because there are too many  2 in my family. My parents are strict. I have to  3  at six o'clock every morning. And I have to make my bedroom4  before breakfast and then go to school. I can't play with my friends after school. I have to do5 homework. After dinner I have to take the dog for    6 walk in the park. I can't watch TV on school nights. I have to 7 the violin for an hour. I can't go to bed late. I have to be in bed 8 nine o'clock. On weekends I have to clean my room and 9 the dishes. I also have to go to learn the violin on Sundays. I'm 10 tired. Can you help me?

                                                                                                                                                                            Yours,

                                                                                                                                                                             Lisa