对于R上可导的任意函数f（x），若满足（x－1）f'(x)$\ge$0，则必有          (　 　)    

指挥家卡拉扬说过，交响乐队要有“团队音”，各自的乐音要顾及整体，不能成为干扰别人的音。启示我们（    ）

如图所示，两平行金属导轨间距l=0.5m，导轨与水平面成θ=37°．导轨上端连接有E=6V、r=1Ω的电源和滑动变阻器．长度也为l的金属棒ab垂直导轨放置且与导轨接触良好，金属棒的质量m=0.2kg、电阻R₀=1Ω，整个装置处在竖直向上的匀强磁场中，金属棒一直静止在导轨上．当滑动变阻器的阻值R=1Ω时金属棒刚好与导轨间无摩擦力．g取10m/s²，sin37°=0.6，cos37°=0.8．求：

根据短文理解从A、B、C、D四个选项中选择最佳答案填空。

    Once a rich woman invited Martin Brown, a famous singer to sing for her friends. But she 1 him to have dinner with them. She told him to eat 2 the servants(仆人).

    After the meal Martin stood up and said to the servants, “Now, my good friends, I 3 for you.” He sang several songs and the servants 4 quite pleased.

    Then the rich woman asked 5 to come to the sitting-room. “We are waiting for your songs. 6 you ready?” the woman asked.

   “I am 7,” Martin said. “I have sung already(已经). I usually sing 8 in one evening, and I can't sing 9.”

    And with a polite(礼貌) “10”, he left the rich woman's house.