根据材料内容，选择正确答案。

    Mr Smith had a week's holiday, so he said, "I'm going to see the sea by train." He put on his best clothes, took a small bag, went to the railway station and got onto the train. He wore a beautiful hat, and he often put his head out of the window during the trip and looked at the beautiful scenery. But suddenly the wind pulled his hat off.

    Mr Smith took his old bag and threw it out of the window quickly too. The others in the train laughed. "Is your bag going to bring back your beautiful hat?" they asked.

    "N0," Mr Smith answered, "but there is no name or address in my hat, and there's a name and an address on the bag. If someone finds both of them, he or she will send me the bag and the hat.''

某养鸡场的鸡一听到主人的哨声就会集结来“吃饭”；这是其主人常用鸡、哨子和米作为训练材料进行不断地训练的结果。则在训练过程中：

将喂米与哨声结合时，是先给予哨声，还是先给予食物？____；

将用于实验的鸡分为实验组和对照组，给予哨声刺激的是____组。

如图，新型汽车的研制中，将汽车模型放在风洞中，让风高速迎面吹来，真实地模拟了汽车在空气中高速行驶的情况，晓彤以地面为参照物，判断汽车是 ____的（选填“静止”或“运动”）；小雪认为此时可以看做汽车在高速行驶，这是以 ____为参照物．

阅读下面的文字，按要求作文。

    年轻的儿子与年迈的父亲散步，父亲走走停停，或是体力不支或是路边的风景吸引了他，儿子不断的催促父亲，并说道：“爸，你要是走不动了，我背你。”父亲回答到“儿子，你老父亲还没那么没用，走那么点路就不行了，散步，急不得，差不多停一下，然后再继续走，走走停停这样会更好！”儿子看着满脸岁月痕迹的老父亲点点头，跟着父亲走走停停，迈向前方。

上面这段文字引起了你的哪些共鸣和引发了怎样的思考？请根据上述材料的含义，写一篇600字至800字的文章。

【注意】①题目自拟，立意自定。②除诗歌外，文体自选。③不得抄袭、套作。④文中不能出现你所在学校的校名，以及教职工、同学和本人的真实姓名。

300mL Al₂（SO₄）₃溶液中，含Al³⁺为1.62g，在该溶液中加入0.1mol•L^﹣1 Ba（OH）₂溶液100mL，反应后溶液中SO₄^2﹣的物质的量浓度约为（　　）