鳃裂囊肿发生于腮腺者主要来源于

A．第一鳃裂

B．第二鳃裂

C．第三鳃裂

D．第四鳃裂

E．胸腺咽管

School education is very important and 小题1:u      . Yet no one can learn 小题2:       at school and a teacher cannot teach his students everything they want to know. His work is to show his students 小题3:_      to learn. He teaches them to read and think alone. So much more is to be learned outside school by the students 小题4:     (他们自己). It is always more important to know how to study by oneself. It is quite easy 小题5:     learn something, but it is difficult to use it to solve 小题6:p      . Great inventors don’t get everything at school, but they still can make many things and 小题7:    (改变) the world a lot. How can the inventors do all of this? One of answer is : They know how to study. A lot of things are not 小题8:t      in the classroom. They get a lot of 小题9:       （知识）by reading outside school. They work 小题10:h    and never give up all their lives.