Bob and Sue are in the same school, 1 they are in different 2. They go to school on weekdays. 3 school, Bob and Sue often play games with 4 friends.

  Class begins 5 eight in the morning. Now Bob and Sue are in their own(自己的) classrooms. They are listening to their 6. Bob's studying English. His teacher is talking 7 English. Sue's 8 a Chinese class. Her teacher is talking 9 writing. They study hard. They love their teachers and they like their 10.

一定质量的氯酸钾和二氧化锰的混合物中，二氧化锰的质量分数为20%，加热后，剩余的固体混合物中二氧化锰的质量分数升高至25%，则氯酸钾的分解百分率为 （     ）