全国艺术院校“桃李杯”舞蹈比赛创立的背景
参考答案：
全国艺术院校"桃李杯"舞蹈比赛创立的背景是：建全舞蹈教育体制，促进舞蹈教学，培养优秀舞蹈表演人才。
在农药、食品毒理学安全评价程序中，属第二阶段试验的是（）
A.急性毒性试验
B.致突变试验
C.亚慢性毒性试验
D.慢性毒性试验
E.人体激发斑贴试验
Alice, your parents were really anxious about you. You ______ home without a word. [ ]
A. mustn't leave
B. needn't leave
C. couldn't have left
D. shouldn't have left
