影响行业景气的内因是()。
A.技术水平变化
B.行业的产品需求变动
C.产业政策变化
D.生产能力变动
参考答案:A, B, C, D
解析:熟悉判断行业生命周期的指标及其变化过程。
请你把下面句子中的错误选出来,并改正。
( ) 1. How much pens are there in your bag? ________________
A B C
( ) 2. — What are these? — They're boxs. ________________
( ) 3. — Where's Tom's picture? — It's on wall. ________________
( ) 4. — What's day is it today? — It's Tuesday. ________________
( ) 5. The cat on the tree is small. ________________
超声的三个基本物理量为
A.声阻抗
B.频率
C.波长
D.声速
E.声密度