What are they doing? They're __________ fun.[ ]
A. has
B. having
C. have
答案：B
I have _____ eraser _____ my pencilcase. [ ]
A. a; in
B. a; at
C. an; in
D. an; at
下列排序方法中，最坏情况下比较次数最少的是______。
A) 简单选择排序 B) 冒泡排序 C) 堆排序 D) 直接插入排序
