1. [单选题]用数组A[0,N-1]存放循环队列的元素值，若其头指针和尾指针分别为front和rear，则循环队列中当前元素的个数为
A. (rear-front+N+1)mod N
B. (rear-front+1)mod N
C. (rear-front-1+N)mod N
D. (rear-front)mod N
2. [单选题]Software is divided into two categories，system software and application software．Please choose one which is differ from other three
A. WindOws 98
B. Word 2000
C. C++compiler
D. FoxBase DBMS
3. [单选题]对于题3所给的C语言程序段if(a>O＆＆b>0)c=c／a；if(a>1‖c>1)c=c+1；执行条件组合覆盖，为使得每一条件取值组合至少执行一次，需要的测试用例数至少是
A. 2
B. 3
C. 4
D. 5
