一个顺序存储的循环队列的队头和队尾指针分别为f和r，则判断队空的条件为（）。
A．f+1==r
B．r+1==f
C．f==0
D．f==r
参考答案：D
用括号中所给单词的正确形式填空。
小题1:She always does her homework ________ (care), and we all like working with her.
小题2:Five days ________ (late), he came to my home again and took away that computer.
小题3: Tom ___________ (begin) to learn Chinese last year.
小题4:Walk along the path, and you ________ (see) a shop on your left.
小题5: I am looking forward to ________ (meet) you in Beijing.
第三方物流客户服务要素包括（）
A.时间
B.可靠
C.方便
D.沟通
