一棵查找二叉树，其节点A，B，C，D，E，F依次存放在一个起始地址为n(假定地址以字节为单位顺序编号)的连续区域中，每个节点占4字节，前二字节存放节点值，后二字节依次放左指针、右指针。
若该查找二叉树的根节点为E，则它的一种可能的前序遍历为 (20) ，相应的层次遍历为 (21) 。在以上两种遍历情况下，节点c的左指针LC的存放地址为 (22) ，LC的内容为 (23) 。节点A的右指针RA的内容为 (24) 。
（21）处填（）。
A．EAFCBD
B．EFACDB
C．EABCFD
D．EACBDF
参考答案：A
| 阅读下面短文，掌握其大意，然后从各小题所给的四个选项中选出最佳选项。 | |||
| Sometimes it's easy to forget that we live in neighborhoods. A picnic 1 a few activities can be fun. Your neighbors will 2 that they want to do things togethermore often. The game of "Getting to 3 You" is a great way for neighbors to learn more about each other.You can 4 by eating at picnic tables. You have to choose an"asker" to ask 5 to the neighbors． The question could be "Can you playins truments (乐器)?" 6 you can't play any instrument, sit down. Then the "asker" will ask,"Can you play just 7 instrument?" If you can play just oneinstrument, please sit down.If the person can play the most instruments, he or she will be the 8 one standing. And he 9 she is tne Wlnner．Neighborhood 10 are not just lots of fun. They also helpbuild a safe living place. | |||
| ( )1. A. in ( )2. A. hear ( )3. A. Know ( )4. A. decide ( )5. A. questions ( )6. A. Or ( )7. A. two ( )8. A. first ( )9. A. so ( )10. A. houses | B．on B. find B. Play B. order B. directions B. Or B. one B. second B. but B. ideas | C. with C．smell C. Bring C．give C．price C. If C. five C．third C．or C．sports | D. to D. smile D. Put D. begin D. ways D. Unless D. three D. last D. and D. picnics |