下列划线字的注音完全正确的一项是（    ）

阅读理解

    Welcome to your future life!

    You get up in the morning and look into the mirror. Your face is firm and young-looking. In 2035, medical technology is better than ever. Many people your age could live to be 150, so at 40, you're not old at all. And your parents just had an anti-aging(抗衰老的) treatment. Now, all three of you look the same age !

    You say to your shirt, “Turn red.” It changes from blue to red. In 2035, “smart clothes” contain particles(粒子) much smaller than the cells in your body. The particles can be programmed to change your clothes' color or pattern.

    You walk into the kitchen. You pick up the milk, but a voice says, “You shouldn't drink that!” Your fridge has read the chip (芯片) that contains information about the milk , and it knows the milk is old . In 2035, every article of food in the grocery store has such a chip.

    It's time to go to work. In 2035, cars drive themselves. Just tell your “smart car” where to go. On the way, you can call a friend using your jacket sleeve(袖子). Such “smart technology” is all around you.

    So will all these things come true? “For new technology to succeed,” says scientist Andrew Zolli , “it has to be so much better that it replaces what we have already.” The Internet is one example --what will be the next?

根据短文内容，选择最佳答案，并将选定答案的字母标号填在题前括号内。

下列关于体液调节的叙述中，不正确的是（   ）

如图，点C是半圆O的半径OB上的动点，作PC$\perp$AB于C．点D是半圆上位于PC左侧的点，连结BD交线段PC于E，且PD=PE．

(1) 求证：PD是⊙O的切线．
(2) 若⊙O的半径为$4\sqrt{3}$,PC=$8\sqrt{3}$,设OC=x,$P{D}^2=y$．
①求关于的函数关系式．
②当$x=\sqrt{3}$时，求$\tan B$的值．