有些史学家认为：“以‘一半是失败了，因而也就是另一半是成功’这种较长远的政治眼光看来，诸如赫鲁晓夫这样伟大的革新者们，只有在当他们的经历成为历史以后，才能得到我们充分的理解和尊敬。”对上述观点理解最准确的是（  ）

①“mn=nm”类比得到“ $a\cdot b=b\cdot a$ ” ；

②“ $\left(m+n\right)t=mt+nt$ ”类比得到“ $\left(a+b\right)\cdot c=a\cdot c+b\cdot c$ ” ；

③“ $\left(m\cdot n\right)t=m\left(n\cdot t\right)$ ”类比得到“ $\left(a\cdot b\right)c=a\left(b\cdot c\right)$ ” .

以上式子中，类比得到的结论正确的个数是（    ）

    When I was a junior high school student in 1980, God gave me a gift, and it was happiness.

    One weekend, I went to visit my grandparents in the countryside. On my way home a car ran over me and broke off my1because of its high speed.

    Several days later when I woke up at the hospital, I realized(意识) I had to spend the rest of my life2arms. How sad I felt at that time! I was full of fears.3slowly I knew I had to face the fact and got over it. I couldn't get my arms back even though I4 every day.

    5, it's easier said than done.6took me nearly half a year to get out of the sadness completely. I got so much from my past story. From then on, I could treat(对待)my life with a7mind. But in our daily life, I often see my classmates8about little things: They get a bad grade on a test; their bus comes9; they don't have a mobile phone but10do, and so on. But I only11life. I was lucky to realize from an accident that it is a waste(浪费) of our life to focus on(集中注意力)12you have lost. We13always think of what we have. So why are so many people unhappy? Someone may say, “My whole life would improve14I have a new car.” But when you get the car what happens? For a whole week you are walking on air. Then you go right back to being unhappy.

    Happiness depends on what we have! It's in our heart. It's a state of mind, even though you own the whole world, you may still feel15. Happiness comes from mastering the art of appreciating(感激) and taking pleasure in what you really have.

天上出现钩钩云，很有可能出现的天气情况是（   ）