在黄河流域的开发与治理过程中，合理的是（    ）

某化学课外小组用海带为原料制取了少量碘水，现用CCl₄从碘水中萃取碘并用分液漏斗分离两种溶液．其实验操作可分解为如下几步：

A．把盛有溶液的分液漏斗放在铁架台的铁圈中；

B．把50mL碘水和15mL CCl₄加入分液漏斗中，并盖好玻璃塞；

C．检验分液漏斗活塞和上口的玻璃塞是否漏液；

D．倒转漏斗用力振荡，并不时旋开活塞放气，最后关闭活塞，把分液漏斗放正；

E．旋开活塞，用烧杯接收溶液；

F．从分液漏斗上口倒出上层水溶液；

G．将漏斗上口的玻璃塞打开或使塞上的凹槽或小孔对准漏斗口上的小孔；

H．静置，分层．就此实验，完成下列填空：

选择下列注音完全正确的一项       (           )

阅读下面短文，从短文后各题所给的四个选项(A、B、C和D)中，选出一个最佳选项。   
    “Daddy, can I have a piece of cake？” my oldest son asked me.
We had just been to the gym and stopped to eat at the restaurant.
    “No，” I replied, “you don't need a piece of cake.”
My son 1 15 in a few days. He 2  over 6 feet tall. He is very slim and athletic in shape . It was not always that way. My wife wrote a book about the challenge and   3   of getting him fit. He now takes it  4  and looks as if he's never been overweight in his life.
    He had a full plate of vegetables and tofu.  He didn't need a piece of cake.  5 ， everything in the restaurant is quite  6 . Our dinners could have  7 a family of seven at a fast food restaurant. That cake probably  8 $5.
    He was silent as he looked at the delicious cakes. I had forgotten that I had walked over to the cake shelf while he was   9 his food from the buffet (自助餐)．
    I looked at my plate. There sitting on the edge was a piece of 10. I looked at it wondering but also knowing how it got there. “We will divide it，” I said.
    A few days later my oldest son was  11me again. We stopped at a   12  . He ordered a sandwich. I then13 two sandwiches. He immediately barked, “Can I have two？” He wanted 14what Daddy had.
    Your kids are very   15 to put on their trays, exactly what you have on yours, and I think this applies to (适用于) more than food. Keep your life plate with only what you want your kids to have.

一位司机驾驶大货车在某路段行驶，由于超速被警察拦住，警察对司机说：“先生，刚才你的车速为70km／h，超速了。”这位司机不满地说：“为什么小车的限速为80km／h，而大车的限速却为60km／h，不合理!”如果让你从物理学角度向司机解释，你会告诉他，这是由于（  ）