阅读下列程序说明和C程序，将应填入程序中(n)处的字句，写在对应栏内。

【程序说明】

本程序先从文件读人各考生的准考证号(设为整型数)及成绩，并将其存放在一棵检索二叉树上，二叉树结点的健值是成绩，每个结点带一链表，链表结点存放取得该成绩的考生的准考证号。然后，程序按中序遍历检索二叉树，从高分到低分输出结果，使每行输出成绩及其取得成绩的考生的准考证号。

【程序】

include ＜ stdio. h ＞

typedef struet idnode {

int id;

struct idnode * next;

} ldNode;

typedef struct marknode I

int mark;

ldNode * head;

struct marknode * left, * right;

} MarkNode;

char fname [ ] = "sp07.dat";

main( )

{ int id, mark;

MarkNode * root = null;

FILE * fp = fopen(fname," r" );

if(!fp) {

printf("file%s open error, \n" , fname);

exit(0);

}

while (!feop(fp)) {

fscanf(fp," %d%d", &id, &mark);

btree(&root, id, mark);

}

fclose(fp);

print(root);

}

btree(MarkNod * * mpptr, int id, int mark)

{ ldNode * ip;

MarkNode *mp = * mpptr;

if (1) {

if (mark==p-＞mark) addldNODE ((2), id);

else if ( mark ＞mp -＞ mark) btree (&top -＞ left, id, mark);

else btree(&mp-＞ right, id, mark);

} else

Imp = ( marknode * ) malloc(sizeo (marknode) );

mp -＞ mark = mark;

mp -＞ left =mp -＞ right = NULL;

(3)

addldNode(&mp -＞ head, id);

(4);

}

}

addldNode(ldNode * * ipp, int id)

{ ldNode * ip = * ipp;

if ((5))addldNode ((6)), id;

else {

ip = (ldNode * )malloc(sizeof(ldNode) );

sp - ＞ id = id;

ip -＞ next = NULL;

(7)

}

}

print(MarkNode * rap)

{ ldNode *ip, *ip0;

if (mp) {

print ( mp -＞ left);

printf(" %6d: \t" ,mp -＞ mark);

ip = mp -＞ head;

while(ip) {

printf(" %6d" ,ip -＞ id);

ip0 =ip;

ip = ip -＞ next;

free (ip0);

}

printf(" \n" ); printf( mp -＞ right); free(mp);

}

}