因声源与接受体相对运动,反射回声频率改变,这称为()。
A.入射角度
B.多普勒效应
C.传播
D.自然反射
E.混响
参考答案:B
阅读短文,判断对(√)错(×)。
Today is Christmas. We have many food in the kitchen. My family are in the kitchen, too. Look, there are
some plates, forks and spoons on the table. Now let's have some turkey.
( ) 1. Today is Christmas.
( ) 2. There are many food in the kitchen.
( ) 3. My family are in the living room.
( ) 4. On the table there are some plates.
( ) 5. Let's have some beef.
下列关于计算机病毒叙述中,不正确的是
A.计算机病毒是一种特殊的具有破坏性的计算机程序
B.计算机病毒具有很强的传染性
C.计算机病毒在任何条件下都可以激发
D.计算机病毒具有依附其他媒体寄生的能力