用邻接表表示图进行广度优先遍历时，通常是采用（）来实现算法的。
A.栈
B.队列
C.树
D.图
参考答案：B
设集合M={x|x2-x＜0}，N={x||x|＜2}，则（ ）
A．M∩N=Φ
B．M∩N=M
C．M∪N=M
D．M∪N=R
Many companies give away small quantities of their produce as samples ______ people can try them
before buying them. [ ]
A. if
B. because
C. so that
D. since
