下列各式中，y随x的变化关系式是正比例函数的是（　　）

根据短文理解，完成下列各题。

    This is our school. There is a very nice 1 in our school. It is big and bright（明亮的）. It has all 2 of books and newspapers in it. We can 3story books, picture books, English books and many 4 books there. We can 5 do some reading there. Maria likes reading very much. She goes to the library every day. Look, she 6 and reading by the window (窗口). Li Ming 7 borrows some books and reads them in it. He likes books.

    I'm going to borrow an 8 story book. Our English teacher often 9 us to do more speaking and reading. I like English very much. I 10 I can do well in English. What about your school?

    I believe it is in my nature to dance by virtue of the beat of my heart, the pulse of my blood and the music in my mind. So I dance1.

    My dining room is now a2ballroom. Each morning when I3the house on the way to make coffee, I turn on the 4and it's dance time! I dance alone to whatever is playing.

    Tango(探戈)is a recent enthusiasm. It's a complex and5dance. The first time I went tango dancing I was too6to get out on the floor7 I stayed on edge of the dance floor when the dancing began. The fancy footwork8me. “Don't make a fool of yourself. Just9it. ” I thought10my mind, an older woman dropped out of the11sat down beside me, and said she had a secret for me. She12“If you do not join the dancing, we will know you are a fool. But if you dance, we will think well of you fo13 Inspired by her14words, I took up the15of tango.

    A friend asked me if I was a little too16“Tango? At your age? You must be out of your mind!" On the contrary, it's a deeply considered17I seek the sharp, scary18that comes from beginning something new, which19all my resources and challenges my body and mind. So, when people say, “Tango? At your age?” I20answer, “Yes!”