He tries ______music well, so he practises ______music every day.

设a∈R，函数的导函数是，若是偶函数，
则曲线在原点处的切线方程为        （   ）

阅读理解
    Hi, I'm Harry. I'm fourteen years old. I live in Taipei, Taiwan. I am a second grader in a junior high school. I'm interested in playing computer games and watching TV. My favorite food is pizza.
    Hello, my name is Dolly. I was born on January 12th. There are four people in my family — my mother, my father, my sister and me. My favorite food is green tea. Now, I am a junior high school student. My hobbies are watching TV and climbing mountains. My best friend Tom lives in Canada. Maybe some day, you will be her friends, too!
    My name is Eric. My hobbies are fishing, reading books and playing computer games. My favorite subject is History, because my dad is a History teacher and I read a lot of books about history. I'm very bad at English, because it's hard for me. My favorite sport is ping-pong. I play ping-pong with my dad and my cousins every weekend.

下列图形中，既是轴对称图形又是中心对称图形的是（   ）

将一定量的丙烷（C₃H₈）和氧气置于一个密封容器中引燃，测得反应前后各物质的质量如表所示：

物质	丙烷	氧气	水	二氧化碳	X
反应前质量（g）	4.4	12.8	0	0	0
反应后质量（g）	0	0	7.2	4.4	a

下列判断正确的是（   ）