阅读理解填词。

　　When Mary Smith was a student, she always w 　　1　　 to be a teacher, because she loved children．When she was twenty-two years old, she began to t 　　2　　 in a small school．She was a good t 　　3　　．The children liked to c 　　4　　 to her class．One day one of the girls in her class s 　　5　　 to her,“Miss Smith, why does a man's hair become w 　　6　　 before his beard(胡子)？”Mary laughed and a 　　7　　,“I don't know, but it happened to my father．”The o 　　8　　 children laughed when they heard this．

　　Then one of the boys said,“I know, Miss Smith!Men's hair become white b 　　9　　 it's sixteen y 　　10　　 older than their beard!”

1．w ________　2．t ________　3．t ________　4．c ________　5．s ________

6．w ________　7．a ________　8．o ________　9．b ________　10．y ________