A boy and his father were walking in the mountains. Suddenly the boy fell，hurt himself，and cried，"AAAhhhhhhhh！！！"To his surprise，he heard the voice repeating（重复），somewhere in the mountain,“AAAhhhhhhhh!!!＂Then the boy shouted，“Who are you?” He received the answer，"Who are you?" He got angry at the answer，so he shouted，"Foolish!" He received the answer，"Foolish！”
He looked at his father and asked，“What’s going on?" The father smiled and said，"My son，listen.”And then he shouted to the mountain，"I love you！”The voice answered，“I love you!”Again the man cried，"You are the best！"The voice answered，“You are the best！”
    The boy was surprised, but did not understand. Then the father explained（解释），"People call this‘Echo’，but really this is Life. It gives you back everything you say or do. Our life is just a reflection（反映）of what we have done. If you want more love in the world，have more love in your heart. If you want to be successful，work hard. This can be used in everything in life. Life will give you back everything you have given to it.”

下图甲表示某种细菌合成精氨酸的途径，图乙表示接种该细菌后可能出现的三种生长曲线。据图分析，下列有关描述中，正确的组合是（  ）

①．图甲显示了该细菌通过调节酶的活性来调节精氨酸的合成
②．从图甲可知，精氨酸的合成是由该细菌的3对等位基因共同控制的
③．图乙的结果可说明加大接种量能缩短细菌生长的调整期
④．精氨酸依赖型突变菌的产生，可能是因为控制酶1合成的基因发生突变

空气有一定的体积，也有一定的形状。（    ）  

下列卤族元素的有关实验，说法正确的是

化学实验室要从含少量铜粉的银、锰（Mn）混合金属粉末中分离出贵金属，并获得一种盐晶体，将有关三种金属随意编号为：A、B、C，并设计了如图流程：