相和大曲中，每段歌唱后再器乐演奏下跳舞的部分叫做（）。
A.艳
B.解
C.趋
D.乱
参考答案：B
When a fire ______ at the National Exhibition in London, at least ten priceless paintings were completely destroyed.
A．brokeoff
B．brokeout
C．brokedown
D．brokeup
设随机变量X和Y的数学期望分别为-2和2，方差分别为1和4．若相关系数为-0.5，则根据切比雪夫不等式P|X+Y|≥6≤______．
