1. 属性
2. hashCode
3. on
4. paused
5. pending
6. runtimeType
7. speaking
8. 方法
9. addEventListener
10. cancel
11. dispatchEvent
12. getVoices
13. noSuchMethod
14. pause
15. removeEventListener
16. resume
17. speak
18. toString
19. 运算符
20. 运算符 ==