Dear Dad，
   Happy birthday to you !
   On this special day I'd like to talk to you1a special way．
   I don't think I am good at2you my thought face to face with you，so I'm writing to show my deep love for you．You're not a rich man or a famous person．But in my heart，you are one of the greatest3 in the world．I am4 you．
   You are5 interested in fame and wealth．You do6 things like paying phone bills on time，and working as a worker in your factory．The smile on your face shows you are pleased with the family．You take good care of my grandparents．You help me with my schoolwork and do some shopping with Mom on Sundays．
   In the past，I didn't care7 you were with me or not．Now I am sorry to say I8 you the respect before．But I am thankful for what you have done for me． I am quite lucky that I have9 a great father．And I feel happy that now I can let you10 how much I love you．You are successful as a son，a husband，a father，and a friend．
   Wish you happy forever!
                                                                                                                                               Yours，

                                                                                                                                               David

①在气体扩散实验中，抽去玻璃板后，红棕色的NO₂气体进入到空气中

②在液体扩散实验中，红墨水滴入热水，热水很快变红

③扩散现象表明，一切物质的分子都在不停地做无规则运动

④温度越高，分子的无规则运动越剧烈．

阅读短文，完成练习。

老猫

    我家的老猫很关心自己的孩子。每次从外面回来，它就先躺下来给小猫喂奶。小猫吃奶的时候，它总要给小猫舔舔毛，似乎在给它们洗澡。哪一只小猫稍有不适，老猫就会绕着这只小猫不停地转，嘴里“喵呜喵呜”地叫着，似乎在问：“小宝贝，你哪里不舒服?快告诉妈妈吧！”