用括号中词的适当形式完成短文。

(playing, because, old, help, movies, favorite, school, best, be, difficult)

     Hi, everybody. My name is Paul. I am American. And I am eleven years     1   . Now I study in Shanghai.

I like my life here. At     2   , the students and teachers are kind (友好的) to me. They often    3    me learn

Chinese, but I still find it very    4    . Of all my subjects, my    5    is English    6    I can speak English very

well. I am the    7    student in English. After school, I like    8    sports. I usually play basketball with my

friends. Sometimes, I go to the    9    with my mother. I like Chinese action movies best, but my mother's

favorite movies    10    comedies.

1._____ 2._____ 3._____ 4._____ 5._____

6._____ 7._____ 8._____ 9._____ 10._____

青云中学需要添置某种教学仪器，方案一：到商家购买，每件需要8元；方案二：学校自己制作，每件需要4元，另外需要制作工具的租用费120元，设需要仪器x件，方案一与方案二的费用分别为y₁（元），y₂（元）。

（1）分别写出y₁，y₂（不必写出自变量的取值范围）；    

（2）若学校需要添置仪器50件，问应采用哪种方案？说明理由。