已知实数 $a,b,c$ 满足 $a>0,b>0,c>0$ ，且 $abc=1$ .

当你练习正步走时，你对地面的压力和压强分别为F₁、p₁；当你立正站立时对地面的压力和压强分别为F₂、p₂，则（　　）

小黄性格开朗，快言快语，小李性格内向，少言寡语；小黄爱好文艺，小李爱好体育。两人的性格、爱好截然不同，但两人也是无话不谈的好朋友。性格和爱好不同的两个人能成为好朋友说明了 （    ）

    It's Saturday morning. My parents and I are on a tour bus. There are about twenty people on the bus. Some are from America, and some are from England and Australia. They are all our friends. We are going to the Great Wall. On the bus, there are two Chinese. One is a woman, the other is a man. The woman is good at English. She is talking with us about the Great Wall. The other people are listening to her. They like the Great Wall. They want to see it very much.