(One day Alice runs after a strange rabbit and comes into a deep hole. She becomes smaller when she wakes up the next day. She finds herself in a wonderland with many amazing things inside.)   
    The Caterpillar(毛毛虫) and Alice looked at each other for some time in silence. At last the Caterpillar took the pipe out of its mouth, and said to her in a tired, sleepy voice.   
   “Who are YOU?” said the Caterpillar.
    This opening for a talk couldn't make Alice at ease. Alice replied, rather shyly, “I----I hardly know, sir, just at present ----at least I know who I was when I got up this morning, but I think I must have been changed several times since then.”
   “What do you mean by that?” said the Caterpillar, “Explain yourself!”
    “I can't explain MYSELF. I'm afraid, sir.” said Alice, “because I'm not myself, you see.”
    “I don't see.” said the Caterpillar.
    “I'm afraid I can't put it more clearly.” Alice replied very politely, “for I can't understand it myself. And being so many different sizes in a day is very puzzling.”
    “It isn't.” said the Caterpillar.
   “Well, perhaps you haven't found it so yet.” said Alice. “But when you have to turn into a chrysalis(蛹，茧)----you will some day, you know ----and then after that into a butterfly, I think you'll feel it a little stranger, won't you?”
   “Not a bit.” said the Caterpillar.
    “Well, perhaps your feelings may be different.” said Alice. “All I know is, it would make ME feel very strange.”
    “You!” said the Caterpillar scornfully(鄙视地). “Who are YOU?” The question brought them back again to the beginning of the talk. Alice felt a little angry because the Caterpillar was making such VERY short sentences. She drew herself up and said very seriously, “I think you ought to tell me who YOU are first.”
   “Why?” said the Caterpillar.
    Here was another puzzling question. As Alice could not think out any good reason, and as the Caterpillar seemed to be very unpleasant, she turned away.
   “Come back!” the Caterpillar called after her. “I've something important to tell you!”
    This certainly gave Alice some hope. Alice turned and came back again.

①y=x+ $\frac{1}{x}$ ；

②y=lgx+log_x10（x＞0，x≠1）；

③y=sinx+ $\frac{1}{\sin x}$ （0＜x≤ $\frac{\pi }{2}$ ）；

④y= $\frac{x^2+3}{\sqrt{x^2+2}}$ ；

⑤y= $\frac{1}{2}$ （x+ $\frac{1}{x-2}$ ）（x＞2）．

其中最小值为2的函数序号是____．

如图所示，将一支点燃的蜡烛放在扬声器的前方，当扬声器发出较强的声音时，可以看到烛焰随着音乐的节奏晃动．扬声器的纸盆由于 ____发出声音，声音通过 ____传到烛焰处，烛焰的晃动说明声音具有 ____

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I think the monkey's ____ (arm) are long.